Sgt. Anthony Sills comforts his wife as they wait outside the army base Thursday. They had to wait for a lockdown to be lifted before they could collect their three-year-old son, who was in daycare on the base. (Jack Plunkett/Associated Press)

A U.S. military officer is in custody after 12 people were killed and 32 were wounded in a shooting rampage at an army base in Fort Hood, Texas, on Thursday.

The suspect was initially reported dead but was later confirmed to be alive. He was identified as Maj. Malik Nadal Hasan, 39, a military mental health doctor who was about to be sent to war, according to law enforcement officials, speaking on condition of anonymity.

"He was shot multiple times at the scene," base commander Lt.-Gen. Robert Cone said. "However, he was not killed as previously reported. He is currently in custody and in stable condition."

Military officials later said he was shot four times and was on a ventilator and unconscious.

Cone said a soldier, armed with two handguns, opened fire at about 1:30 p.m. CT in the base's Soldier Readiness Center, where troops go through medical screening before being deployed overseas or after returning from a posting.

Maj. Malik Nadal Hasan is reported to be the gunman who opened fire in Fort Hood, Texas, killing 12 people. (U.S. Department of Defence/Reuters)

Cone also clarified the status of a female civilian officer who had been reported killed.

"We know that the female officer is alive, just out of surgery and in stable condition. She is believed to be the first-responder who shot the suspect."

Cone said one of the guns used was a semi-automatic weapon. He said he couldn't speculate on reports that the shooter was targeting specific people.

Hasan was born in Virginia and graduated from Virginia Tech, the site of a mass shooting in 2007. He was also a fellow in disaster and preventive psychiatry in the department of psychiatry at the F. Edward Hébert School of Medicine.

Hasan worked for six years at the Walter Reed Army Hospital, where he reportedly received a poor performance evaluation, said officials who had access to his military records. He was transferred to Fort Hood in July.

U.S. Senator Kay Bailey Hutchison said Hasan was not happy that he was about to be deployed, although it is unclear if Hasan was destined for Afghanistan or Iraq.

Wanted troop withdrawal

Terry Lee, a retired army colonel, told Fox News he had worked with Hasan, who hoped U.S. President Barack Obama would pull troops out of both wars. Lee said Hasan got into frequent arguments with others in the military who supported the wars.

The officials said Hasan had come to their attention at least six months before the attack because of internet postings that appeared to come from him that discussed suicide bombings and other threats. Officials are still working to confirm Hasan's connection to the postings, but an official investigation was never opened.

One of the postings that authorities reviewed is a blog that equates suicide bombers with a soldier throwing himself on a grenade to save the lives of his comrades.

"He is a brave hero that sacrificed his life for a more noble cause," the posting says.

Faizul Khan, a former imam at a mosque Hasan attended in Silver Spring, Md., said he spoke often with Hasan about how Hasan wanted to find a wife. Hasan was a lifelong Muslim and attended prayers regularly, often in his army uniform, Khan said.

Obama called the Texas shooting "a horrific outburst of violence" and pledged support for the Fort Hood community.

"It's difficult enough when we lose these brave Americans in battles overseas," Obama said. "It is horrifying that they should come under fire at an army base on American soil."

Three other soldiers were apprehended after Thursday's attack, but all have since been released.

The soldiers who witnessed the attack would not have been carrying weapons to defend themselves, said Specialist Jerry Richard, who works at Fort Hood. Soldiers are only armed on the base during training exercises.

"Overseas, you are ready for it," he said. "But here, you can't even defend yourself."

Fort Hood is between Austin and Waco. It is reported to be the largest U.S. military base in the world and home to almost 5,000 officers, more than 45,000 enlisted military personnel and roughly 9,000 civilian employees.

A graduation ceremony for soldiers who finished college courses while deployed was going on nearby at the time of the shooting, said Sgt. Rebekah Lampman, a Fort Hood spokeswoman.