Examining Trends, Impacts, Drivers, and Policy Implications of Active School Shooter Incidents: A Research Overview

Abstract 

In the context of alarming trends in school shootings and mass shootings experienced today,  school districts, practitioners and policymakers need to adapt to combat this evolving threat. To  understand the gaps in existing research, it is necessary to examine the trends, drivers, impacts,  and policy implications of active shooter incidents. This essay offers a review of recently  published academic research on active shooter incidents, with a focus on school shootings.  The first section highlights publications on drivers and impacts of active shooter incidents.  The second section reviews some of the latest scholarly evaluations of policies put in place to  counter school shootings and mass shootings broadly. 

Active School Shooting Trends 

Active school shooting incidents remain a major threat to homeland security and public safety  in the United States. The term “active school shooter” is defined as the act of an individual’s  firearm being brandished, fired, or when a bullet hits school property for any reason regardless  of the number of victims, time of day, day of week, or motivation.¹ During the first ever  recorded attack in 1767, four Lenape American Indian men entered a school in present day Greencastle, Pennsylvania, which resulted in eleven deaths and two injured.² 255 years later, the number of school shootings has exploded. In 2022 alone, there were 302 school shootings,  a 90.40% increase from 2000.³ Since 1970, over 2,232 active shooter incidents have occurred  within a K-12 school environment and disturbingly, over 1,554 K-12 school shootings have  been recorded since 2000.⁴ The tragic school shooting incident that set a foundational need for  stricter school security is the 1999 Columbine High School shooting which killed thirteen people  and injured twenty-four others.⁵ Since 2020, a total of 681 school shootings have been recorded  which marked the highest increase in school shooting incidents recorded in United States  history.⁶ Though statistically rare in occurrence, more than 331,000 students have fallen victim  to gun violence at school since Columbine.⁷ On average, the United States has experienced  approximately forty-one school-targeted shootings every year since 1970.⁸ 

Sadly, active shooter incidents in American schools are part of a ubiquitous threat associated  with mass shooting and gun violence. Mass shooting is defined as four or more individuals  shot and/or killed at the same time and place not including the shooter.⁹ In 2022 alone (as of  December 31), there were 648 recorded mass shootings in the U.S.¹⁰ This represents a 57.87%  increase compared to 2014. Current trends in the number of casualties are also alarming. In  2022, a total of 1,672 children and teens (age 0-17) were killed, and 4,476 children and teens (age 0-17) were injured during mass shooting attacks between January 1 and December 31.¹¹ These casualty numbers represent a 50.50% increase compared to 2014. In comparative terms,  these trends make the United States an outlier among developed countries. Australia, for  instance, recorded twelve mass shooting incidents from 1981 to 2013 while the U.S. recorded  seventy-three incidents over the same period.¹² In Scotland, 682 cases were recorded over a  twelve-year span (2010-2022) in comparison to 599 cases in a single year (2022) in the United  States.¹³ These comparative differences further highlight the magnitude of mass shooting rates  in the U.S. This essay aims to examine the trends, impacts, drivers, and policy implications of  active shooters while offering recommendations for prevention practices. 

Impacts of Active Shooter Incidents 

Beyond the detrimental impacts, existing research has provided evidence showing that school  shootings produce additional devastating consequences for American society. For instance, the  trauma endured following an event can impact the economic outcomes of students. A recent  study found that students exposed to incidents are 6.3 percent less likely to be employed and  will lose approximately $115,550 in their total lifetime income.¹⁴ From a social standpoint, the  intensity of active shooter drills in schools impacts the psychological well-being of students,  faculty, and staff. As these drills increasingly seek to mimic real-life scenarios, participants are  exposed to high risks of stress and anxiety. Following a school shooter drill, a study found,  students and faculty might respectively see a forty-two and thirty-nine percent increase in stress  and anxiety and depression.¹⁵ 

Drivers of Active School Shooters 

Recent scholarship on the drivers of school shootings and of the broader issue of mass  shootings focus on the psychological, socioeconomic, and structural factors that motivate  violent behavior and influence the extent to which perpetrators commit violent acts. For  instance, a group of researchers recently examined the relationship between adverse childhood  experiences (ACEs) and violent behavior displayed by current students.¹⁶ Using the 2013  Minnesota Student Survey, they examined household and family characteristics, with a focus on  reported ACEs and negative household and family exposures, to see if exposure to ACEs caused  an increase in school violence. They found that fifteen percent of students reported verbal  abuse, thirteen percent reported physical abuse, eleven percent reported parental substance  abuse, seven percent reported parental intimate partner violence, six percent reported  an incarcerated parent, and three percent reported sexual abuse. Furthermore, subgroup  participants reported thirty-nine percent of victims, forty percent of perpetrators, and sixty two percent of perpetrator-victims reported one or more household/family ACE. Out of this  subgroup, the rate of on-campus violence increased significantly.  

Other recent studies have examined risk factors such as social capital, social ties within the  community, income inequality, socioeconomic status, and others to better understand the  correlation of risk factors and mass shootings in general. In a study published in 2019, Daniel Kim used geolocated gun homicide incident data and U.S. census data from 2010 to 2015  and found that individuals living alone in poverty-stricken communities with little to no social  ties to the community are correlated with a twenty-seven percent increase in gun homicides.  Additionally, the increase in income inequality and social mobility were linked to a fifteen  percent increase in firearm related mass shootings. A decrease in these social determinants  lowered the risk of gun related homicides by thirty-two percent. The lack of accessible resources  and funding in welfare and education over time has contributed to an increase in mass shooting  incidents, especially in young children and adults.¹⁷ 

In a recent investigation of the link between income inequality and mass shootings, Roy Kwon  and Joseph Cabrera analyzed data from the U.S. Census, FBI, and media outlets from 1990 to  2015 across a sample of 3,144 counties in the United States. They found that counties that  experienced a decrease in income inequality also experienced a decrease in mass shootings at  a rate of six per one thousand counties. Additionally, the researchers found that the increase  in income inequality leads to anger and violence, which directly influences the risks of mass  shootings. On the latter, counties that experienced an increase in income inequality also  experienced an increase in mass shootings at a rate of thirty per one thousand counties.¹⁸ 

Recent studies on mass shootings have also examined the role of fear factors. For instance,  Maurizio Porfiri and his colleagues were interested in investigating whether individuals purchase  firearms for self-protection because they fear being the next victim of a mass shooting. The  researchers examined the correlation of mass shooting fear factors and firearm acquisitions at  the state level. In a state-level study that relied on databases from the Washington Post, Mother  Jones, and FBI reports, they found that media coverage increased fear associated with the lack of  firearm background checks, especially in Connecticut and Hawaii, as no background checks were  reported for an extended period which in turn increased firearm purchases for self-protection.¹⁹ 

Policy Response and Implications to School Shootings 

Research has revolved around the Safe School Initiative. The result of a collaborative effort  launched by the U.S. Secret Service and the U.S. Department of Education in June 1999  following the attack at Columbine High School, the Safe School Initiative sought to examine  school shooting incidents to understand the thinking, planning, and other behaviors engaged in  by perpetrators.²⁰ Since Bryan Vossekuil and their colleagues’ publication of the initial report in  2002, a Safe School Initiative Act has been adopted in numerous local and state jurisdictions in  the hopes of providing a safer school environment for all students and faculty by implementing  mental health counseling and resources within school districts.²¹ To support the overarching  goal of the Safe School Initiative Act, threat assessments, which provide information regarding  the extent of which a student poses a risk to themselves or others, have slowly been adopted  across states.²² Threat assessments serve as a mitigation tool by identifying leakage and the  ability to accurately intercept prior to an incident. As the debate continues as to whether  threat assessments should include leakage and mental health together, policy and program  implementation have both been vastly understudied and underfunded. 

The initial study explored pre-attack behaviors and communications associated with 37 incidents  involving 41 perpetrators that occurred in the United States from 1974 through 2000. The findings  indicate that, in most of the cases, other individuals (classmates, teachers, friends, parents)  reported a noticeable change in perpetrator behavior and even had knowledge that an attack may  occur. Additionally, seventy-eight percent of the perpetrators had never received a mental health  evaluation despite having a history of exhibiting mental health symptoms and behaviors.²³ 

The 2002 Safe School Initiative report brought to light two factors that are still being  investigated by academic researchers today. Findings of earlier studies showed that eighty one percent of cases involved at least one person knowledgeable of the thinking or planning  of a school attack by another person.²⁴ More recent studies have corroborated these results. Researchers Adam Lankford, Krista Adkins, and Eric Madfis for example, found that fifty-nine  percent of cases involved two or more people having knowledge of the thinking and planning  of a school attack.²⁵ When examining forty-one reported cases of targeted school violence that  occurred in K-12 schools in the U.S. from 2008 to 2017, a 2019 study by the U.S. Secret Service  National Threat Assessment Center (NTAC) found that all cases examined identified some form  of leakage either in violent behavior or through verbal communication.²⁶ 

Other studies seem to confirm the idea that proper understanding and management of the  leakage phenomenon could help prevent school tragedies. All these studies commonly point  to the critical role of leakage in relation to efficient intelligence analysis within local law  enforcement agencies. In their study of Active Shooter Incidents in the U.S. between 2000 and  2013, researchers James Silver, Andre Simons, and Sarah Craun found that out of the thirty  recorded active shooter cases in 2017, each perpetrator displayed four to five concerning  violent behaviors that were noticeable to others over time, thus leaking their violent intent. In  terms of reporting behaviors to law enforcement, the researchers also found responses included  fifty-four percent of the population not reporting and forty-one percent reporting behaviors to  law enforcement.²⁷ 

The ongoing conversations on the role of leakage suggest that several challenges must be  overcome before an instance of leakage can be successfully turned into a prevention tool.  First, third parties (e.g., parents, classmates, teachers, and school administrators) must  accurately identify cues leaked by the perpetrators. It is thus important, from research and  policy standpoints, to shed light on the drivers of and barriers to accurate identification of  leaked cues. It should be noted that just because forty-one percent reported violent behaviors,  it does not mean the leakage was considered or mitigated against by local law enforcement.  While tying together active shooters and the presence of leakage, this problem area could  greatly benefit from understanding how reporting leakage in the context of human behavior  impacts intelligence gathering operations at the local level and the ability to mitigate against a  foreshadowed event.  

Both studies showed that leakage clues were not intercepted due to lack of training, funding,  and accountability. In opposition to the supporting arguments, researcher Linda McCash found  that school districts in Florida were not in favor of implementing school-based mental health  programs due to key challenges such as difficulty determining organizational placement of the program, authority and accountability, organizational support, ongoing funding to maintain the  program, and unclear program procedures, thus inferring that there was no governmental  guidance on how to adopt and maintain this critical policy to its fullest capability. Aside from  the overall difficulty of maintaining such programs, other researchers have questioned the  accuracy of threat assessments.²⁸ Contrasting arguments expressed at the National Summit on K-12 School Safety and Security included the likelihood of targeting groups that are not actual  school threats and missing those who fall under the high-risk category. Wrongly targeted  groups include children of color, children with disabilities, and low-income families and  households. Safety directors who attended the summit also argued that threat assessments  should include a whole child approach rather than one that is structured around a mental  health emphasis.²⁹ Threat assessments should not become profiling tools to avoid the  potential increase within the school to prison pipeline. An apparent gap within the study of  threat assessments includes the lack of data on human behavior and the impacts of leakage.  Much of the previous research includes studies pertaining to human perception but does not  answer the questions on human behavior in terms of reporting crime, effectively reacting to  the threat, and taking a more proactive approach in deterring school shooting events when  foreshadowed clues are available.  

Some of the research on policy responses to active school shooter incidents have revolved  around the provisions of HIPAA’s Privacy Rule. If done diligently, school threat assessments  could mitigate against the risk and probability of a school shooter event. Law enforcement  organizations can utilize school threat assessments as a proactive prevention tool that models data in real world settings.³⁰ Research has questioned whether mental health information  should be included in assessments but it is presently considered a separate factor.  

As threat assessment teams strive toward accurately identifying leakage, sharing information,  and mitigating against potential threats, HIPAA’s Privacy Rule sets boundaries on under what  circumstances protected health information, specifically mental health records, is disclosed  to law enforcement. The term “leakage,” is defined as an instance when a perpetrator of  school shooting, intentionally or unintentionally, reveals cues to feelings, thoughts, fantasies,  and attitudes through verbal or nonverbal communications that may signal an impending act  of violence.³¹ In the case of a high-risk student, the Privacy Rule authorizes defined medical  agencies to disclose protected health information to law enforcement officials without written  consent when responding to an off-site medical emergency with the purpose of alerting  law enforcement about criminal activity. From an ethical standpoint, professionals are only  permitted to disclose information to law enforcement when imminent danger is perceived,  and the interception would prevent or lessen the posed threat to the individual or to others.³² What appears to be lacking within the policy discussion is understanding the barriers between HIPAA and diverse law enforcement ethical standards that limit what investigations take place, roles within investigations, and jurisdictional capabilities.³³ Key conceptual terms, such as  imminent danger and criminal activity, are not clearly defined. As definitions may vary across  organizations, the criteria to meet the standards of the definitions become unclear and up  to interpretation, which can result in missed opportunities, loss of life, and law enforcement  prevention and response failures.

In the context of privacy challenges within school threat assessments, researchers Nicole Jones  and Angel Gray utilized a case study approach to identify the ethical and legal challenges faced  by law enforcement during the investigatory information gathering process in North Carolina.  It should be noted that all identification information was redacted from the case study. While  focusing on the case background investigation section, the researchers examined a threat  assessment that identified a high-risk male student who leaked written detailed plans of a  school shooting at his high school. The student also had a repeat history of extreme violence,  aggression, involuntary psychiatric hospitalizations, and substance abuse along with numerous  psychiatric diagnoses. While conducting interviews, law enforcement experienced a lack of  cooperation amongst hospital staff regarding patient health records during all hospitalizations.³⁴ The researchers found that even though HIPAA’s Privacy Rule permits the disclosure of  protected health information to law enforcement, the North Carolina General Assembly enacted  a statutory provision that made any confidential medical disclosures to law enforcement  where information used could prevent or reduce the imminent danger nonmandatory.³⁵ It  can be suggested from a legal standpoint, that any information obtained by law enforcement  outside the scope of public records was considered in violation of HIPAA’s Privacy Rule and  North Carolina’s statutory provision, due to the student not meeting the hospital criteria for  an evaluation or commitment for treatment.³⁶ This highlights why medical disclosures to law  enforcement are often underreported, as some hospital staff wanted to report concerning  behavior but did not in accordance with the statutory provision. It is unclear how imminent  danger was defined as there was a detailed plan, previously identified violent history, and  extensive mental illness history. 

While the Association of Threat Assessment Professionals (ATAP) provided ethical and practical  guidelines to threat assessment teams, they also recognized that ethical standards vary by  profession. The researchers found that ethically, that state only permits law enforcement to  collect information for their investigation from public records to ensure confidentiality.³⁷ From  a law enforcement prevention perspective, it can also be inferred that the ethical and legal  challenges combined limited the capabilities of the threat assessment teams’ investigatory  capabilities.³⁸ A possible explanation for the limited capabilities stems from how broadly  written the ATAP’s Code of Ethical Conduct is. Broadly defined standards make it unclear  what the intended roles of law enforcement are and may be of limited use in making quick thinking decisions on ethical practices within threat assessments.³⁹ In essence, because  threat assessments are a newly adopted school mitigation approach, law enforcement ethical  codes have not adapted to reflect the current threat which contributes to the failures seen in  prevention and response efforts.  

Recommended Prevention Practices 

Over the past two decades, a growing body of literature has identified and challenged the  overarching failures seen during previous school shooting events. As the focus has shifted  towards implementing threat assessments, missed opportunities have accentuated the negative  consequences of ineffective information sharing methods, training, and response efforts.  Researchers James Fox and Jenna Savage used the Virginia Tech shooting as a case study to provide recommendations on best prevention practices. The researchers compiled seven  recommendations, but only two will be discussed for the purpose of understanding HIPAA,  threat assessments, interagency relationships, and crisis communication specifically. In terms of  privacy, the researchers recommended that all campus personnel should be trained on HIPAA’s  Privacy Rule and its functionality before, during, and after school shooting events. Not being  trained on the limits and allowances of the Privacy Rule can cause underutilization of critical  information received which can carry a significant loss while at the same time, overreaching  can reduce trust, and increase unnecessary student profiling and campus litigation. As HIPAA  permits disclosures without consent in extreme cases, there is still confusion regarding when  to report extreme violent behavior and what criteria must be met to legally override student  privacy.⁴⁰ Like the previously mentioned study, there is a lack of defined standards as to what  actions constitute exceptions to HIPAA’s Privacy Rule.  

From a preparedness standpoint, researchers James Fox and Jenna Savage recommended  certifying mutual aid agreements with local health agencies and additional key stakeholders to  increase resources and response efforts. As there are currently some mental health resources  on college campuses, certifying necessary relationships with external agencies would drastically  increase the type of mental health resources available and how quickly they can be drawn  upon when needed.⁴¹ It has been suggested in research that establishing effective interagency  relationships will support the flow of information sharing, and hopefully encourage reporting to  law enforcement. Establishing interagency connections will allow for a more cohesive training  and exercise practice where the roles of each responding agency are clearly defined.⁴² While the  research study could have benefitted from defining what the missed opportunities were in the  recommendations, the research still highlights a common gap within HIPAA’s Privacy Rule and its  impact on school shooter prevention and response efforts.  

The research discussed so far has shown the qualitative findings and recommendations  in current research but has overlooked the benefit of presenting quantitative data. The  researchers offered recommendations from the Virginia Tech shooting but did not clearly  define the missed opportunities that influenced the recommendations made. ⁴³ For instance, they discussed the need to train campus personnel on HIPAA’s Privacy Rule and the  exceptions to the policy in imminent situations and to establish interagency relationships with  relevant healthcare professionals and external stakeholders but did not discuss the failures  noted during the actual event that would have influenced the recommendations provided.⁴⁴ This would have made the literature clearer to the audience which is unfamiliar with the  events that took place. As previously mentioned, recommendations were made of seventy  percent of the previous reports, but they never provided information on who is included  within that seventy percent population.⁴⁵ On a broader scale, research within this sector could greatly benefit from quantitative data. While focusing on the overall limitations, it is important to conduct quantitative studies to understand what drives individuals to report crime (or not) to law enforcement in correlation with HIPAA. This will allow researchers to  examine specific drivers, impacts, and policy challenges that influence underreporting which  in turn, can clarify the limitations to HIPAA during school shooting threat assessments. 

While examining school shooting events, researchers Jaclyn Schildkraut and her colleagues  utilized a case study approach to examine the events leading up to the Parkland shooting to  identify the challenges and failures experienced. Additionally, they used the Path to Intended  Violence Model to illustrate the perpetrator’s journey toward violence that foreshadowed the  devastating events seen. This model was originally used to assess the behaviors of individuals  who had assassinated or were at high-risk of assassinating public figures, but over time, the  model found overlapping similarities in pre-attack behaviors by school shooters. The model  consists of variables such as grievances, ideation, research, planning, preparation, breaching,  and policy implications— all of which are considered factors in school threat assessments.⁴⁶ As various sources were utilized for the case study, the perpetrator’s mental health records  were not included in accordance with HIPAA, but HIPAA’s Privacy Rule was overlooked in  terms of the reporting to law enforcement in imminent events prior to the incident. In fact, the model found that approximately thirty people had first-hand knowledge of the violent  behavior prior to the shooting but were downplayed as jokes and never followed up on  by local or federal law enforcement agencies.⁴⁷ A possible explanation could be due to the  bystander effect, in that individuals were not taking responsibility since an abundance of  others were aware of the displayed behaviors at the same time, or they feared the potential  consequences of reporting and the perpetrator finding out.  

To summarize the findings from the model, the researchers found the Parkland perpetrator  experienced chronic and prolonged stressors that intertwined with a lack of social support,  which exacerbated the effects of the event. In terms of ideation, the perpetrator was leaking  suicidal tendencies that date back to his childhood. During the research and planning  phase, the perpetrator had the school bell schedule on his phone which showed the times  students were in the classroom versus in the hallway changing classes. He also researched  combat breathing techniques. Preparation is mostly uniform across school shooting events  in that it includes obtaining a firearm(s) and ammunition to carry out the act. In this case  the perpetrator used an AR-15 with numerous rounds of ammunition that were purchased  over time. Lastly, there was no prior breaching involved, meaning that officials did not find  the perpetrator conducting a dry run of the attack.⁴⁸ The summarized findings highlight the  substantial evidence that support the value of threat assessments and their ability to identify  and mitigate against potential catastrophic events. While applying what has been discussed  about school threat assessments and HIPAA’s Privacy Rule, it can be presumed that the  overall missed opportunity was the nonexistent threat assessment and the lack of reporting  from medical professionals to intercept the events that occurred. Given the detailed analysis  of events leading up to the school shooting, there is a disconnect between law enforcement  and medical professionals. The recommendations offered by researchers James Fox and  Jenna Savage can be applied to the Parkland case while focusing on training, education, and  interagency relationships. The research did not give reasons to why only HIPAA was applied  in terms of confidentiality and not the Privacy Rule, considering the extensive mental health  history that was later publicized after the shooting and trial, thus furthering the gap in  understanding the drivers and causes of underreporting.

School shootings highlight the impact of chaos on individuals and systems to effectively execute  plans. As most school shooting cases to date contained leaked evidence that foreshowed the  incident along with extensive mental illness histories, the abruptness of each case has also  identified its negative impact on preparedness, prevention, and response efforts to reduce  the number of lives lost. The challenges discussed surrounding HIPAA’s Privacy Rule showcase  a small portion that contribute to the overarching problem: the unclear understanding of underreporting and the lack of accountability taken due to broadly written policies.  

Conclusion 

Unfortunately, active school shooting incidents are a unique issue growing rapidly in the  United States today. The alarming trends dating back to the Columbine school shooting in  1999, highlighted the significant and impactful increase of such catastrophic events. Examining  the drivers and impacts of school shootings provides researchers with a comprehensive  discussion of active school shooter incidents and the areas needed to be further explored in  future research. Both the Safe School Initiative Act and HIPAA’s Privacy Rule were discussed to  highlight the successes and failures of current policy enacted to mitigate against the next school  shooting incident. Collectively, this research overview provided a review of research and studies  that highlight critical components for understanding the active school shooter phenomenon.  For instance, school shootings have increased 90.40% from 2000 to 2022.⁴⁹ Research has also  examined the impacts of school shootings and found a loss of total income earned over a  lifetime, and increased psychological effects such as stress and anxiety. Studies have shown  psychological, socioeconomic, structural factors that correlate with increased trends over time.  Empirical studies are needed to advance the literature on active school shooters to influence  policies to better protect our schools and students. 

Notes 

1. David Riedman, “Active Shooter Situations at K-12 Schools: 1970-2022,” K-12 Shooting Database, accessed  March 1, 2023, https://k12ssdb.org/active-shooter . 
2. Ibid. 
3. Jillian Peterson, “Mass Public Shootings in the United States, 1966-Present,” The Violence Project Mass  Shooting Database, last modified March 2021, https://www.theviolenceproject.org/mass-shooter database/ ; Riedman, “Active Shooter Situations 1970-2022.” 
4. Riedman, “Active Shooter Situations 1970-2022.” 
5. Ibid. 
6. Ibid.  
7. Cox et al., “338,000 Experienced Gun Violence.” 
8. Riedman, “Active Shooter Situations 1970-2022.”  
9. “Total Number of GV Deaths- All Causes,” Gun Violence Archive, last modified March 8, 2023, https://www. gunviolencearchive.org/past-tolls . 
10. Ibid. 
11. Ibid.  
12. Bricknell et al., “Mass Shooting and Firearm Control: Comparing Australia and the United States,”  Australian Institute of Criminology, accessed October 25, 2022, https://www.aic.gov.au/sites/default/ files/2020-06/draft_of_trends_issues_paper_mass_shootings_and_firearm_control_comparing_australia_ and_the_united_states_submitted_to_peer_review.pdf . 
13. “Recorded Crimes and Offenses Involving Firearms, Scotland, 2018-19 and 2019-2022.” Cabinet Secretary  for Justice and Veterans, last modified October 27, 2022, https://www.gov.scot/publications/homicide scotland-2019-2020/pages/5/ . 
14. Cabral et al., 2022, “Trauma at School: The Impacts of Shootings on Students’ Human Capital and Economic  Outcomes,” NBER Working Paper 28311, National Bureau of Economic Research, Cambridge, MA. 
15. El Sherif et al., Impacts of School Shooter Drills on the Psychological Well-Being of American K-12 School  Communities: A Social Media Study,” Humanities & Social Science Communications 8, no: 1 (2021): 1-14,  https://doi.org/10.1057/s41599-021-00993-6 . 
16. Forster et al., “Adverse Childhood Experiences and School-Based Victimization and Perpetration,” Journal  of Interpersonal Violence 35, no. 3-4 (2020): 662-681, https://doi.org/10.1177/0886260517689885 .  
17. Daniel Kim, “Social Determinants of Health in Relation to Fire-Arm Related Homicide in the United States:  A Nationwide Multilevel Cross-Sectional Study,” PLOS Medicine 16, no. 12 (2019): 13, https://doi.org/10.1371/ journal.pmed.1002978 . 
18. Roy Kwon and Joseph F. Cabrera, “Income Inequality and Mass Shootings in the United States,” BMC Public  Health 19, no. 1 (2019): 4, https://doi.org/10.1186/s12889-019-7490-x .
19. Porfiri et al., “Self-Protection Versus Fear of Stricter Firearm Regulations: Examining the Drivers of Firearm  Acquisitions in The Aftermath of Mass Shootings,” Patterns 1, no. 6 (2020): 9-10, https://doi.org/10.1016/j. patter.2020.100082 . 
20. Vossekuil et al., “The Final Report and Findings of The Safe School Initiative: Implications for The  Prevention of School Attacks in the United States,” U.S. Department of Justice Office of Justice Programs,  last modified July 2004, https://www2.ed.gov/admins/lead/safety/preventingattacksreport.pdf . 
21. Rebecca G. Cowan and Rebekah F. Cole, “Understudied and Underfunded: Potential Causes of Mass  Shootings and Implications for Counseling Research,” Journal of Social Change 12, no. 1 (2020): 128, https:// doi.org/10.5590/JOSC.2020.12.1.10. 
22. Kingston et al., “Building Schools’ Readiness to Implement a Comprehensive Approach to School Safety,”  Clinical Child and Family Psychology Review 21, no. 4 (2018): 436, https://doi.org/10.1007/s10567-018-0264-7. 
23. Vossekuil et al., “Final Report of Safe School Initiative,” 21.  
24. Vossekuil et al., “Final Report of Safe School Initiative,” 21.  
25. Lankford et al., “Are the Deadliest Mass Shooting Preventable?” 330.  
26. Alathari et al., “Protecting America’s Schools: A U.S. Secret Service Analysis of Targeted School Violence,”  United States Secret Service National Threat Assessment Center, last accessed March 1, 2023, https:// www.secretservice.gov/sites/default/files/2020-04/Protecting_Americas_Schools.pdf . 
27. Silver et al., “A Study of Pre-Attack Behaviors of Active Shooters in the United States Between 2000 and  2013,” accessed March 1, 2023, https://www.fbi.gov/file-repository/pre-attack-behaviors-of-active shooters-in-us-2000-2013.pdf/view .  
28. Linda McCash, “Mental Health Services in Schools: A Qualitative Analysis of Challenges to Implementation,  Operation, and Sustainability,” Psychology in Schools 42, no. 4 (2005): 365, https://doi.org/10.1002/ pits.20063 .  
29. Mark Keierleber, “Can Educators and Police Predict the Next School Shooter?” The74, last modified  November 2, 2022, https://www.the74million.org/article/can-educators-and-police-predict-the-next school-shooter/ .  
30. Nicole T. Jones and Angel E. Gray, “Threat Assessment and Management: Identifying the Ethical and Legal  Challenges within a Law Enforcement Setting,” Journal of Threat Assessment and Management 7, no. 1-2  (2020): 98, https://doi.org/10.1037/tam0000145 . 
31. Adam Lankford, Krista Grace Adkins, and Eric Madfis, “Are the Deadliest Mass Shooting Preventable?  An Assessment of Leakage, Information Reported to Law Enforcement, and Firearm Acquisition Prior to  Attacks in the United States,” Journal of Contemporary Criminal Justice 35, no. 3 (2019): 316, https://doi. org/10.1177/1043986219840231 ; Schildkraut et al., “Parkland Mass Shooting,” 1. 
32. “Disclosures for Law Enforcement Purposes: When does the Privacy Rule Allow Covered Entities to  Disclose Protected Health Information to Law Enforcement Officials, U.S. Department of Health & Human  Services, last modified December 28, 2022, https://www.hhs.gov/hipaa/for-professionals/faq/505/what does-the-privacy-rule-allow-covered-entities-to-disclose-to-law-enforcement-officials/index.html . 
33. Jones and Gray, “Threat Assessment and Management,” 99-101.  
34. Ibid., 105.
35. U.S. Department of Health & Human Services, “Disclosures for Law Enforcement.”. Jones and Gray, “Threat  Assessment and Management,” 106. 
36. Jones and Gray, “Threat Assessment and Management,” 106-107.  
37. “Disclosures for Law Enforcement Purposes,” U.S. Department of Health & Human Services. 38. Jones and Gray, “Threat Assessment and Management,” 106-107.  
38. Ibid.,100.  
39. James Alan Fox and Jenna Savage, “Mass Murder Goes to College: An Examination of Changes on College  Campuses Following Virginia Tech,” American Behavioral Scientist 52, no. 10 (2009): 1472, https://doi. org/10.1177/0002764209332558 .  
40. Ibid., 1472.  
41. Ibid., 1472. 
42. Fox and Savage, “Mass Murder Goes to College,” 1472. 
43. Ibid., 1472. 
44. Ibid., 1472. 
45. Schildkraut et al., “The Parkland Mass Shooting and the Path to Intended Violence: A Case Study of  Missed Opportunities and Avenues for Future Prevention,” Homicide Studies, (2022): 2, https://doi. org/10.1177/10887679211062518 
46. Ibid., 6.  
47. Ibid., 2-3. 
48. Peterson, “Mass Public Shootings in the United States, 1966-Present,”