The soldier who killed three people before committing suicide in an attack on the same Texas military base where more than a dozen people were slain in 2009 had shown no recent risks of violence, authorities said Thursday.
The shooter, identified as Ivan Lopez by Texas Rep. Michael McCaul, chairman of the House Homeland Security Committee, opened fire at Fort Hood on Wednesday afternoon. He wounded more than a dozen others.
Military officials declined to formally identify the gunman, an enlisted soldier with the rank of specialist, by name until his family members had been officially notified.
But Army Secretary John McHugh said the soldier saw no combat during a four-month deployment to Iraq as a truck driver from August to December 2011. A review of his service record showed no Purple Heart, which indicates he never was wounded.
The soldier saw a psychiatrist last month and showed no "sign of any likely violence either to himself or others," McHugh said. His record shows "no involvement with extremist organizations of any kind."
"We're not making any assumptions by that. We're going to keep an open mind and an open investigation. We will go where the facts lead us. And possible extremist involvement is still being looked at very, very carefully. He had a clean record in terms of his behavior," McHugh said.
Within hours of the Wednesday attack, investigators started looking into whether the soldier had lingering psychological trauma from his time in Iraq. Fort Hood's senior officer, Lt. Gen. Mark Milley, said the gunman had sought help for depression, anxiety and other problems, and was taking medication.
Among the possibilities investigators were exploring 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," a federal law enforcement official who spoke on condition of anonymity, because he was not authorized to discuss the case by name, said hours after the shooting Wednesday.
The official said authorities would begin by speaking with the man's wife, and expected to search his home and any computers he owned.
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 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.
His weapon recently was purchased locally and was not registered to be on the base, Milley said. He arrived at Fort Hood in February from Fort Bliss, Texas.
McHugh said the soldier, a Puerto Rico native, joined the island's National Guard in 1999 and served on a yearlong peace-keeping mission in Egypt's Sinai Peninsula in the mid-2000s. He then enlisted with the Army in 2008, McHugh said.
Those injured Wednesday were taken to the base hospital and other local hospitals. At least three of the nine patients at Scott & White Memorial Hospital in Temple still were listed in critical condition Thursday.
The shootings immediately revived memories of the 2009 shooting rampage on Fort Hood, the deadliest attack on a domestic military installation in U.S. history. Thirteen people were killed and more than 30 were wounded.
Until an all-clear siren sounded hours after Wednesday's shooting began, relatives of soldiers waited anxiously for news about their loved ones.
"The last two hours have been the most nerve-wracking I've ever felt," said Tayra DeHart, 33, who had earlier heard from her husband that he was safe but was waiting to hear from him again.
Army psychiatrist Nidal Hasan was convicted last year for the November 2009 mass shooting at Fort Hood. According to trial testimony, he walked into a crowded building, shouted "Allahu Akbar!" - Arabic for "God is great!" - and opened fire. The rampage ended when Hasan was shot in the back by base police officers.
Hasan, now paralyzed from the waist down, is on death row at the military prison at Fort Leavenworth in Kansas. He has said he acted to protect Islamic insurgents abroad from American aggression.
After that shooting, the military tightened base security nationwide. That included issuing security personnel long-barreled weapons, adding an insider-attack scenario to their training, and strengthening ties to local law enforcement. The military also joined an FBI intelligence-sharing program aimed at identifying terror threats.
In September, a former Navy man opened fire at the Washington Navy Yard, leaving 13 people dead, including the gunman. After that shooting, Defense Secretary Chuck Hagel ordered the Pentagon to review security at all U.S. defense installations worldwide and examine the granting of security clearances that allow access to them.