An Iraq War veteran being treated for mental illness opened fire at Fort Hood, killing three people and wounding 16 others before committing suicide, in an attack on the same Texas military base where more than a dozen people were slain in 2009, authorities said.
Within hours of the Wednesday attack, investigators started looking into whether the man's combat experience had caused lingering psychological trauma. Fort Hood's senior officer, Lt. Gen. Mark Milley, said the gunman had sought help for depression, anxiety and other problems.
Among the possibilities investigators planned to explore was whether a fight or argument on the base triggered the attack.
"We have to find all those witnesses, the witnesses to every one of those shootings, and find out what his actions were, and what was said to the victims,'' said a federal law enforcement official who spoke on condition of anonymity, because he was not authorized to discuss the case by name.
The official said authorities would begin by speaking with the man's wife, and expected to search his home and any computers he owned.
The shooter was identified as Ivan Lopez by Texas Rep. Michael McCaul, chairman of the House Homeland Security Committee. But the congressman offered no other details, and the military declined to identify the gunman until his family members had been notified.
Lopez apparently walked into a building Wednesday afternoon and began firing a .45-caliber semi-automatic pistol. He then got into a vehicle and continued firing before entering another building, but he was eventually confronted by military police in a parking lot, according to Milley, senior officer on the base.
As he came within 20 feet (6 meters) of an officer, the gunman put his hands up but then reached under his jacket and pulled out his gun. The officer drew her own weapon, and the suspect put his gun to his head and pulled the trigger a final time, Milley said.
The gunman, who served in Iraq for four months in 2011, had been undergoing an assessment before the attack to determine if he had post-traumatic stress disorder, Milley said.
He arrived at Fort Hood in February from another base in Texas. He was taking medication, and there were reports that he had complained after returning from Iraq about suffering a traumatic brain injury, Milley said. The commander did not elaborate.
The gunman was never wounded in action, according to military records, and there was no indication the attack was related