Originally published November 5, 2009 at 1 p.m., updated November 5, 2009 at 3:17 p.m.
A mass shooting rocked one of the nation's largest military posts on Thursday after at least one U.S. soldier opened fire inside Fort Hood in Texas.
At least 12 people were killed, including the shooter, and more than 31 were injured in the incident, according to U.S. military officials. Most, if not all of the victims are U.S. military personnel.
The shooting occurred at the Soldier Readiness Center, where troops deploying to Iraq and Afghanistan receive last-minute medical checkups.
One U.S. soldier, armed with at least two handguns, started firing around 1:30 pm local time before he was eventually shot and killed by emergency personnel responding to the incident, Lt. Gen. Bob Cone said. The Associated Press and other media report that the name of the suspected shooter is Maj. Malik Nadal Hassan, a medical professional who worked at the base.
Authorities said they also apprehended two additional U.S. soldiers for questioning.
The motive behind the shootings was not immediately clear, officials said.
"We've had a terrible tragedy here at Fort Hood here today," Cone told reporters outside the gate to Fort Hood a few hours after the shooting. "This is all under investigation."
Military officials immediately locked down the sprawling post, which covers some 335 square miles in central Texas.
The post is a prime deployment point for the conflicts in Afghanistan and Iraq. Roughly half of Fort Hood's 44,000 soldiers were serving in Iraq or Afghanistan as of August 2009.
More than 520 soldiers from Fort Hood have been killed since the U.S. invasions of Iraq and Afghanistan.
In Washington, President Obama expressed his sympathies to the wounded and the families of the slain soldiers, and he pledged a full inquiry.
"It's difficult enough when we lose these brave Americans in battles overseas," he says. "It is horrifying that they come under fire at a military base on American soil."
The first shots were fired 30 minutes before a graduation ceremony was scheduled to begin at a nearby theater.
The wounded soldiers were taken to nearby hospitals, which put out an urgent call for blood donations.
The incident sparked sad echoes of an earlier mass shooting.
The massive Fort Hood is located near Killeen, Texas, which was the site of one of the nation's worst mass shootings in history. On Oct. 16, 1991, George Hennard shot and killed 23 people in a Luby's Cafeteria restaurant before turning the gun on himself. He also wounded 20 people.