Obama to attend Fort Hood rampage memorial

US President Barack Obama will Tuesday attend a memorial service here to honor victims of the wild shooting rampage on the military base in which 13 people died, the White House said.

Investigators were meanwhile working around the clock to uncover why the Muslim US army doctor, Major Nidal Malik Hasan, suspected in the killings that also wounded 30 people.

"All evidence at this point indicates the suspect allegedly acted alone," Chris Grey, spokesman for the US Army criminal investigation division (CID), told reporters Saturday, adding that no motive had yet been established.

Criminal investigators were poring over evidence to determine if the alleged shooter -- who survived shooting wounds and is under guard at a military hospital -- was motivated by Islamist ideology or had snapped under the pressure of his job counseling soldiers traumatized by combat.Related article: Witnesses speak of carnage

In his weekly radio address on Saturday, Obama called the mass-shooting "one of the most devastating ever committed on an American military base."

At a press conference later Saturday, Colonel John Rossi, deputy commander of Fort Hood, told reporters that "17 victims and the suspect remain hospitalized."

An initial search of 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.

Poignant details released here Saturday 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, and 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.

Specialist Ryan Hill, 28, came to the base with his young daughter Emma to put flowers and candles at the main gates as a mark of respect to the victims.

"It makes me mad. I don't how somebody can commit an act like that," Hill told AFP. "Those soldiers were ready to take off and deploy and they won't even get to do that."

The bodies of those killed were taken Friday to the same mortuary at Dover Air Base in Delaware that handles fallen soldiers from the wars in Afghanistan and Iraq.

Obama in his radio address hailed the response of soldiers and civilians at the scene who rushed to help victims, tearing off bullet-riddled clothes to treat the injured and using blouses as tourniquets.

The president 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 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, who investigators believe fired more than 100 rounds during the incident, shout "Allahu Akbar!" (God is greatest) before unloading a semiautomatic weapon and a handgun at a troop processing center.

Troops based in Fort Hood, by area the world's largest US military base, have suffered the highest number of casualties and have undertaken multiple tours of duty in Iraq and Afghanistan.

The shooting has meanwhile 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.