At least 13 people were killed and 30 more wounded in a shooting at Ford Hood in Texas on Thursday, and authorities are still piecing together a troubling portrait of the man thought responsible on Friday. The Army says the gunman is Major Nidal Malik Hasan, a psychiatrist born in Virginia and raised in the United States. Hasan, who is alive but in a coma and on a ventilator, allegedly shouted "Allahu Akbar!" before starting his shooting rampage, which is Arabic for "God is great."

The base commander says the gunman used “a very calm and measured approach” in his shooting. He was exiting the building when police officers Kimberly Munley and Mark Todd arrived, and he shot Munley in the thigh. Hasan allegedly then began to reload his weapon, and Munley shot him four times. An Army officer then used his belt to make a tourniquet on Munley's leg. She's in stable condition.

Click Below to View Photos from the Fort Hood Shooting

Hasan, whom officials now say acted alone, allegedly carried two weapons, one of them semi-automatic, which explains the high casualty count. Hasan, 39, is a psychiatrist recently reassigned from Walter Reed Army Medical Center in Washington, D.C., to work with soldiers at Fort Hood. His cousin said at Walter Reed, Hasan treated soldiers returning from war with combat stress and PTSD and was afraid of his own impending deployment to Afghanistan. Hasan had recently undergone a peer review; his fellow doctors found no fault with the care he provided.

His aunt told The Washington Post that her nephew tried to get out of his Army contract for several years but couldn't. She says he felt harassed because of his Muslim faith. Hasan reportedly drew the attention of federal law enforcement six months ago for online posts about suicide bombings and other threats including "a blog that equates suicide bombers with a soldier throwing himself on a grenade to save the lives of his comrades." An imam at a Maryland mosque he attended said that Hasan was a lifelong Muslim, but showed little sign of political or religious zealotry.

Hasan's cousin Nader Hasan described the Afghanistan deployment as Hasan's "worst nightmare." Nader says his cousin was dealing with harassment from his colleagues and had hired a military attorney to help him. "We are shocked. We just found out on the news that he was being deployed," Nader Hasan told Fox News. One of Hasan's military co-workers told Fox News' Shepard Smith that the major was "aggressive" and cited religious callings as a Muslim, and Smith read accounts of racially charged harassment that Hasan allegedly underwent. Watch both interviews below.

On Thursday morning, Major Nidal Malik Hasan gave most of his belongings to his neighbor. Awhile later, a security-camera video showed him at a convenience store on Thursday morning buying snacks in a white robe and skullcap—traditional Muslim garb.

NPR talked to two psychiatrists who trained with Hasan in 2007, one of whom said that when he saw the news, he thought, " That completely fits the person I knew." The doctors said Hasan could be belligerent and "once gave a bizarre lecture to the medical staff in which he said the Quran teaches that infidels should have their heads cut off and set on fire." Around the same time, he regularly called the war on terror " a war against Islam." But Hasan's bosses at Walter Reed said he did a good job.

Hidden Camera Footage Allegedly From Day of Shooting

Suspect Made 'Outlandish' Comments

Cousin: Hasan is a 'Good American'

Obama Laments 'Horrific Violent Outburst'

Fort Hood's History of Military-on-Military Violence

Thursday's mass shooting was not the first violent event Fort Hood has suffered. Fox News reports the following violent incidents:

• In September 2008, a 21-year-old Fort Hood soldier fatally shot his lieutenant, and then himself, during an off-base confrontation in his apartment. Fox News continues:
• "Two months later a New York parolee with an extensive criminal record was executed for robbing, raping and fatally shooting an Army medic at her apartment near Fort Hood."
• "In July of 2009, Fort Hood Spc. Armano Baca was charged with murdering fellow soldier Spc. Ryan Richard Schlack from Wisconsin." Baca and Schlock had recently returned from tours in Iraq.
• "Three months ago Spc. Jared Lee Bottorff was charged with murder after a shooting at a party near the post."