(Killeen, TX) -- Investigators are trying to figure out a motive behind the worst massacre in history on a U.S. military installation.  Soldiers caught in the gunfire say the suspect, a fellow comrade, shouted words in Arabic as he opened fire.

Soldiers mowed down in the Ft. Hood shooting rampage are painting the picture of a methodical gunman.

Lt. Gen. Robert Cone/Ft. Hood Commanding General: I talked to one man last night, he was shot 4 times, by the same shooter, when he moved, he said I made the mistake of moving and I was shot again.

Suspect Nidal Malik Hasan, an Army psychiatrist, seen in a convenience store video the day of the shooting wearing Muslin dress, reportedly shouted  "Allahu Akbar!" - an Arabic phrase for "God is great!" before he opened fire.  The Army says he killed 13 soldiers and one civilian during his spree inside Ft. Hood's Solider Readiness Center.  Another 30 were wounded.

Lt. Gen. Robert Cone/Ft. Hood Commanding General: "At one point the gunman realized a lot of the soldiers had started to escape, walked and started shooting outside the building," said Lt. Gen. Robert Cone, Commanding General of Ft. Hood.

Hundreds of soldiers were inside the facility, but weren't armed because they don't usually carry their army weapons on base. A nearby active response team rushed to the scene to stop the gunman.

Civilian police officer Kimberly Munley fired at Hasan four times. She was hit too, but according to the base commander is okay and talking on the phone with friends.  Hasan, a 39-year-old major, is in stable condition and on a ventilator.

The mother of Amber Bahr, a 19-year old at Ft. Hood, learned that her daughter took a bullet in the back. "My baby girl was  shot, that's not supposed to happen," said Bahr's mother, Lisa Phund.

But Bahr didn't let that stop her from helping other soldiers.  "A young lady who realizes that her battle buddy is hurt takes her blouse off ties a tourniquet, carries him outside to safety, then realizes she herself is shot," said Lt. Gen. Cone, of Bahr's actions.

Investigators have yet to speak with Hasan. But colleagues say he was about  to be deployed to Iraq and didn't want to go.  

Late this morning, President Obama ordered U.S. flags at federal facilities lowered to half staff through Veterans Day, in honor of those killed at Ft. Hood.



(Joel Brown - CBS News)