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Investigators on Saturday worked to uncover the motives of a Muslim US army doctor suspected of killing 13 people and wounding 30 others in a shooting rampage at a US military base.
An initial search of Major Nidal Malik Hasan's computer revealed no direct exchanges with known extremists, but US Army and FBI officials had yet to rule out possible links to terrorist groups, US media reported.
Earlier this year, the Federal Bureau of Investigation learned of Internet postings by a man calling himself Nidal Hasan that expressed support for suicide bombings.
Investigators were not able to determine yet whether the writer was Major Hasan, but the details fueled concerns that authorities may have missed warning signs prior to the attack at Fort Hood, Texas.
Neighbors reportedly said Hasan, 39, was in a rush when he gave away his belongings -- including a Koran -- shortly before Thursday's bloody shooting spree.
"I'm not going to need them," he told one neighbor, Patricia Villa, according to The New York Times, handing over bags of vegetables, a mattress and clothing.
A US-born Muslim of Palestinian heritage, Hasan had voiced dismay over US wars in Islamic countries and was distraught that he was about to be deployed to Afghanistan.
He reportedly said the US struggle against terror threats was a "war on Muslims," while his family alleged he was the target of prejudice and harassment over his Islamic faith.
Criminal investigators were poring over evidence to determine if the alleged shooter -- who was under guard at a hospital -- was motivated by Islamist political ideology or had snapped under the pressure of his job counseling soldiers traumatized by combat.
In Texas, poignant details of each of those killed in the rampage drove home the scale of the tragedy.
The victims included a 21-year-old mother-to-be Private Francheska Velez, who was due to return home to Chicago for maternity leave after a tour in Iraq; 56-year-old John Gaffaney, a psychiatric nurse who had just persuaded the military to let him return to active duty for deployment in Iraq; Private First Class Kham Xiong, 23, a father of three whose own father had fought communist forces in Laos during the Vietnam war.
The bodies of those killed were taken to the same mortuary at Dover Air Base in Delaware that handles fallen soldiers from the wars in Afghanistan and Iraq.
But at least some of those shot were making a good recovery, according to Roy Smythe, a top surgeon at the Scott and White Hospital in Temple, Texas,
"Of the ten original patients who were admitted, four have gone home, one may go home today," he said.
"We had initially six patients in the surgical intensive care unit, as of this morning we only have two left.
"There is a possibility that some of these patients will be physically impaired for the rest of their lives and there is certainly no doubt that many of them will be psychologically impaired for the rest of their lives"
President Barack Obama on Saturday described the shooting as "one of the most devastating ever committed on an American military base."
"And yet, even as we saw the worst of human nature on full display, we also saw the best of America," he added.
The president hailed the soldiers and civilians who rushed to help victims, tearing off bullet-riddled clothes to treat the injured and using blouses as tourniquets.
Obama ordered flags to fly at half-staff at the White House and federal buildings, as troops at home and abroad held a minute's silence to mourn the dead.
Hasan was moved from a civilian to a military hospital, in part for security reasons, Fort Hood deputy commander Colonel John Rossi told reporters.
Hasan was shot and seriously wounded by a female civilian police officer who was being hailed as a heroine for ending his deadly rampage.
Witnesses reportedly heard Hasan shout "Allahu Akbar!" (God is greatest) as he opened fire in a troop processing center with a semiautomatic weapon and a handgun.
Rossi said investigators believe Hasan fired more than 100 rounds during the incident.
It took place at Fort Hood, by area the world's largest US military base, one which has borne the brunt of the wars in Iraq and Afghanistan.
Troops based here have suffered the highest number of casualties and have undertaken multiple tours of duty.
The shooting has raised delicate questions about Muslim soldiers serving in the military, as some commentators warned of an Islamic "fifth column" infiltrating the army while Islamic groups called for calm amid concerns of a backlash.
Casey said after a visit to the base that he too feared a backlash.
