(CNN) -- Eleven people plus a gunman were dead and 31 wounded after the gunman opened fire Thursday on a soldier-processing center at Fort Hood, Texas, officials said.
The gunman was a soldier, and two other soldiers have been detained as suspects, Army Lt. Gen. Bob Cone said.
The slain gunman was identified as Maj. Malik Nadal Hasan, according to a law enforcement source. The source believes he is 39 or 40 years old.
Ten of the other dead also were soldiers, while the remaining one was a civilian police officer who was working as a contractor on the base, Cone said.
Two of the injured were in "very serious" condition, Fort Hood spokesman Christopher Hogue said.
More than one shooter may have been involved, Cone said.
"All the casualties took place at the initial incident, that took place at 13:30 [1:30 p.m. CT], at the soldier readiness facility," Cone said.
The primary shooter had two weapons, both handguns, he said.
"The local police response forces were there relatively quickly and killed the confirmed shooter," Cone said.
President Obama called the shootings "tragic" and "a horrific outburst of violence." He expressed his condolences for the shooting victims.
"These are men and women who have made the selfless and courageous decision to risk, and at times give, their lives to protect the rest of us on a daily basis," Obama said. "It's difficult enough when we lose these brave Americans in battles overseas. It is horrifying that they should come under fire at an Army base on American soil."
Officials at Fort Hood, which is the Army's largest U.S. post, were asking people there to stay away from windows, CNN affiliate KXXV said. The incident took place at the sports dome, now known as the soldier readiness area, the station reported.
A congressional aide said he was on the post to attend a graduation service when he saw a soldier with blood on his uniform near the building where the service was being held, the Austin American-Statesman reported.
Greg Schannep, an aide to U.S. Rep. John Carter, said the soldier ran past him and said a man was shooting. He said the soldier appeared to be injured in a shoulder, the American-Statesman reported.............
