The alleged gunman in the killing of 13 servicemembers at Fort Hood Army base participated in a Homeland Security Disaster Preparation program, according to a report for the event.

The report, posted by Gawker, shows a "Nidal Hasan" from the "Uniformed Services University School of Medicine was a task force event participant," the site notes. :Other participants included Senate and House staffers, Department of Homeland Security officials, Defense Department officials, and reporters for Politico, the Washington Post and the London Times."

"The task force was not officially affiliated with the White House," added Gawker investigations editor John Cook. "It was a project of the Homeland Security Policy Institute, an independent thinktank housed at George Washington University, aimed at drafting policy recommendations for the incoming Obama administration."

Military officials on Friday struggled to understand why a Muslim army psychiatrist due to be deployed to Afghanistan went on a shooting rampage at this huge military base that left 13 dead and 30 wounded.

Major Nidal Malik Hasan, 39, an army-trained specialist in combat stress, was under guard and in stable condition on a ventilator at a nearby civilian hospital after being shot and seriously wounded during Thursday's bloodshed.

He has not spoken about his actions, officials said.

"We're not going to speculate about motives," Colonel John Rossi, deputy commander of Fort Hood, told reporters here early on Friday.

With AFP.