Editor's note: Last updated Friday at 5:17 PM EST 

The FBI, military intelligence, other intelligence agencies, and the Army Criminal Investigation Command are aggressively investigating the background of Army psychiatrist, Major Malik Nadal Hasan, a Muslim who had espoused jihadism and objected to US involvement in the Middle East who Thursday afternoon allegedly opened fire with two weapons at soldiers preparing to deploy to the war on terrorism at the Fort Hood Soldiers’ Readiness Processing Center.

Thirteen soldiers were killed and 30 wounded, including Hasan, who is said to be in stable condition and not talking to authorities.

Base commander Lt. Gen. Robert Cone said witnesses heard Hasan shout out "Allah Akbar!" before watching him open fire on fellow soldiers. Cone said at a late Friday press briefing that he could not rule out Hasan’s alleged actions as an act of terrorism, but that evidence at the time did not indicate that it was.

In 2005, scholar Daniel Pipes coined the phrase “sudden jihad syndrome” to describe sudden murderous rampages and actions by otherwise normal people driven by Islamist impulses, which there are terrible examples of, as described by Homeland Security Today editor David Silverberg in his new HSToday.us column.

Former Fort Hood commander Lt. Col. Allen West (Ret), who is a Republican candidate for Congress in Florida's 22nd District, warned that terrorists are infiltrating the military and trying to convert US soldiers.

In a statement titled, "Terrorists Are infiltrating Military," West said "this enemy preys on downtrodden soldiers and teaches them extremism will lift them up. Our soldiers are being brainwashed."

The tragedy at Fort Hood does come against the backdrop of intelligence indicating that Al Qaeda would like to specifically target American military personnel via new media, and even physical infiltration of jihadists into the military, in an effort to conduct acts of jihad like the violence Hasan allegedly engaged in at Fort Hood.

So far there is no evidence that jihadist propaganda on the Internet played any role in Hasan's apparent sudden extremist views.

But former CIA Bin Laden unit chief Michael Scheuer told FOX News Friday afternoon that “for years it’s been very clear that two of the targets for Al Qaeda and other Islamist groups for recruitment were in the US military and in the US military system.”

Continuing, Scheuer criticized the government for quickly ruling out terrorism, saying it has done this before “because they are politically correct – they don’t want to talk about religion. In the last 24 hours it appears that this Major was a very devout Muslim, and his depending deployment overseas put him in a position where he was going to be assisting in killing other Muslims, and that’s a very big decision for a Muslim to do; not only killing another Muslim, but killing them on behalf of an infidel or a Christian.”

Armed Forces Journal reported in January 2005 about Muslim members of the US military who took actions against America in the name of jihad.

While noting that they were drawing no conclusions about Hasan's motivations, counterterrorist officials pointed out to HSToday.us that numerous top Islamist terrorist organizations' leaders are or have been doctors and physicians.

Hasan was to be deployed to the front in the war on terrorism. According to a variety of people who knew him, Hasan objected to his deployment because he did not want to have to confront members of his own faith.

Authorities said Hasan had to reload his weapons given the number of shots that were fired – an indication that he methodically premeditated what he did. Witnesses said he appeared calm and collected as he fired on soldiers.

While FBI and other officials early on downplayed the incident as having been an act of terrorism, officials told HSToday.us Thursday evening Hasan’s alleged actions could have been a personal act of jihad against soldiers heading to the frontlines of the war on terrorism, noting that Hasan’s background is under intense scrutiny.

Federal law enforcement officials said that jihadist-like Internet postings they believe were written by Hasan had put him on their radar screen six months ago. Some of the postings allegedly discussed a variety of jihadist thinking. According to reports and intelligence sources, no official investigation was opened, however.

Federal authorities have seized Hasan's computers.

Retired Army Col. Terry Lee who had worked with Hasan said Thursday evening Hasan had repeatedly expressed sympathies for Isalmist jihadism and “that Muslims should stand up and fight against the aggressor” - even “strap[ping] on suicide vests.”

Hall said Hasan's extremist talk had been reported, but did not know whether any investigation was opened.

In response to thwarted domestic jihadist bombing plots this fall - which included schemes against US military installations - the US Northern Command’s (NORTHCOM) Joint Operations Center issued a “Force Protection Directive” that cautioned domestic Defense Department personnel against becoming complacent to staying alert to terrorism threats.

The “For Official Use Only” directive, which was obtained by HSToday.us, advised CONUS military personnel to be aware of “the potential for complacency given the lack of specific information relative to DoD personnel, installations, and facilities” involved in the recent surge of disrupted terrorist attacks.

The NORTHCOM directive stated “complacency” is NORTHCOM's “top concern.”

According to reports, Hasan had become increasingly agitated by what he claimed was harassment from fellow soldiers for being Muslim. However, Abdul Rashid Abdullah, deputy director of the American Muslim Armed Forces and Veterans Affairs Council, told Fox News that the nonprofit group has not received a single report recently of a US soldier being harassed "simply because he was Muslim."

Authorities told HSToday.us Friday afternoon that had Hasan "snapped earlier, he possibly could have done higher-level damage," as one put it. They were referring to a Homeland Security Policy Institute (HSPI) task force meeting last year aimed at drafting policy recommendations for the incoming Obama administration that Hasan appears to have attended. According to the task force's May 2009 report, participants included congressional staffers, Department of Homeland Security, Defense, and State Department officials, and reporters.

[Editor's note: Friday afternoon HSPI issued the following statement: "In his capacity as Disaster & Preventive Psychiatry Fellow at the Uniformed Services University School of Medicine, Nidal Hasan registered ('RSVP’d') to attend as an audience member a number of Homeland Security Policy Institute events in the period June 2008 to February 2009. All of these events were open to the public. At no time has Nidal Hasan been affiliated with HSPI or The George Washington University]

Walid Phares, an Islamic scholar who is Director of the Future of Terrorism Project at the Foundation for Defense of Democracies and author of, Future Jihad: Terrorist Strategies against the West, and The War of Ideas: Jihadism against Democracy, wrote Friday that "the main question we should be asking is when did Maj. Malik Nadal Hasan become radicalized and who indoctrinated him? Everything else will fall in place once we have these answers."

In an op-ed in the Christian Science Monitor, Jonathan Zimmerman, who teaches history and education at New York University, wrote that Hasan’s actions do not mean that “we should view every Islamic immigrant with suspicion, but it does mean that we have a serious security problem on our hands. And it's simply irrational to deny it.”

While early reports stated Hasan had only recently converted to Islam, in an interview with FOX News Thursday night, Hasan’s cousin, Nadar Hasan, said Maj. Hasan “[has] always been Muslim,” adding he was “Muslim prior to joining the military” prior to the 9/11 attacks.

The cousin said Hasan was “intelligent, articulate ... made six figures” and had never expressed any violent tendencies. “He was a good American ... We’re shocked ... we’re trying to make sense of it ...”

What seems clear from a variety of reports is that Hasan was a “very devout” Muslim born in Virginia to Jordanian immigrants.

FOX News reported that a former neighbor of Hasan's in Silver Spring, Maryland interviewed by the FBI said Hasan had the word "Allah" on his door.

Robert Spencer, the director of the Jihad Watch blog and the author of numerous books on Islam and jihad, stated that “no one, no one at all, in the mainstream media is discussing jihad as a motivation. It’s all about ‘snapping,’ ’not wanting to go to war,'" adding, "If this turns out to be a jihad attack, watch for the president to caution against 'backlash' and Islamophobia.'"

Obama urged people not to jump to conclusions while law enforcement investigates the shootings.

"We don't know all the answers yet and I would caution against jumping to conclusions until we have all the facts," Obama said.

Bloggers, pundits, and commenters are warning of an anti-Muslim backlash in response to Hasan’s actions.

Meanwhile, a report by a conservative news organization stated in its lead that Hasan "played a homeland security advisory role in President Barack Obama's transition into the White House, according to a key university policy institute document." But as scrutiny of the report determined, that assertion is false at best.

US-based Muslim groups have publicly condemned Hasan’s actions and said if convicted, Hasan should be prosecuted to the full extent of the law. Some Muslim groups also have said they are concerned about renewed anti-Muslim backlash.

Republican Sen. John Cornyn said in a statement that “it is imperative that we take the time to gather all the facts, as it would be irresponsible to be the source of rumors or inaccurate information regarding such a horrific event. Once we have ascertained all the facts, working with our military leaders and law enforcement officials on the ground, we can determine what exactly happened at Fort Hood today and how to prevent something like this from ever happening again.”

According to the official records, Hasan graduated Virginia Tech University with a bachelor's degree in biochemistry in 1997. He obtained a medical degree in 2001 and later a Master’s Degree in public health from the Uniformed Services University of the Health Sciences F. Edward Herbert School of Medicine, in Bethesda, Maryland, where he was trained in disaster and preventive psychiatry. He completed residency in psychiatry at Walter Reed Army Medical Center in Washington, DC in 2007.

He reportedly was transferred to Fort Hood in July after working at Walter Reed for for six years.

Virginia state medical licensing records list a Nidal Malik Hasan as a psychiatrist for the Army Medical Corps, with his primary practice at Darnall Army Medical Center at Fort Hood.

Officials speaking on condition of anonymity told news organizations Hasan had received a poor performance evaluation while at Walter Reed.

But Col. Steve Braverman, Fort Hood’s hospital commander, was quoted saying "I'm not aware of any problems … We had no problems with his job performance."

Colonel Kimberly Kesling, deputy commander of clinical services at Fort Hood's Darnall Army Medical Center, told the Wall Street Journal that, “to date, [Hasan] had been performing quite well." He appeared to be a dedicated professional, the Journal reported Kesling as saying.

But a source told National Public Radio that Hasan had been put on probation during his postgraduate work for proselytizing about his Muslim faith with patients and colleagues, which has authorities investigating whether Hasan may have tried to convert any Muslim soldiers that he may have counseled about extremist Islamist ideology.

Records show Hasan was awarded the National Defense Service Medal, the Global War on Terrorism Service Medal, and the Army Service Ribbon.

The Senate Armed Services Committee is seeking a "detailed accounting" of the circumstances surrounding the shootings at Fort Hood.