Colonel Ben Danner said the suspect was shot four times and was in critical condition.
The man was identified as Major Nidal Malik Hasan, a 39-year-old from Virginia.
President Obama called the shooting at the Soldier Readiness Center, where soldiers who are about to be deployed or who are returning undergo medical screening, “a horrific outburst of violence.’’
“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.’’
There was no official word on motive. Hasan had transferred to Fort Hood in July from Walter Reed Medical Center, where he received a poor performance evaluation, according to an official who spoke on condition of anonymity because he was not authorized to discuss the case publicly.
Senator Kay Bailey Hutchison, Republican of Texas, said generals at Fort Hood told her that Hasan was about to deploy overseas. Retired Colonel Terry Lee, who said he had worked with Hasan, told Fox News Hasan was being sent to Afghanistan.
Lee said that Hasan had hoped Obama would pull troops out of Afghanistan and Iraq, and that the major argued frequently with others in the military who supported the wars.
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.
The shooter used two pistols, one of them semiautomatic. Neither was military-issued, Danner said. Video from the scene showed police patrolling the area with handguns and rifles, ducking behind buildings for cover. Sirens could be heard wailing, and a woman’s voice on a public-address system urged people to take cover.
“I was confused and just shocked,’’ said Specialist Jerry Richard, 27, who works at the center but was not on duty during the shooting. “Overseas you are ready for it. But here you can’t even defend yourself.’’
Soldiers at Fort Hood do not carry weapons unless they are engaged in training exercises.