The soldier who went on a shooting rampage at Fort Hood, Texas, had a history of mental illness and had been taking medication for anxiety and depression, but Army leaders said Thursday that they had not considered him a potential threat.
Investigators said they were still trying to clarify a motive for the attack but were focusing on the fragile state of mind of Spc. Ivan Antonio Lopez, a 34-year-old military truck driver and Iraq veteran. Officials said he killed three fellow soldiers and took his own life Wednesday in an outburst of gunfire at one of the country's largest military installations.
Spc. Lopez, a married father of four, was given a full psychiatric evaluation last month and had been prescribed "a number of drugs," including the sleep aid Ambien, according to Army Secretary John McHugh. But the Army psychiatrist who last saw Spc. Lopez found no "sign of likely violence, either to himself or to others," Mr. McHugh told a Senate panel.
Another Army leader described Spc. Lopez's health in more dire terms. "We have very strong evidence that he had a medical history that indicates unstable psychiatric or psychological conditions," Lt. Gen. Mark Milley, commanding general of Fort Hood, said at a news conference. "We believe that is the fundamental, underlying causal factor."
Around the same time that Spc. Lopez visited the Army psychiatrist, he legally purchased the .45-caliber Smith & Wesson semiautomatic pistol that he used in the shooting, Army officials said.
The soldier bought the firearm March 1 from Guns Galore, a store in nearby Killeen, Texas, officials said. The shop is the same one that sold a semiautomatic pistol to Maj. Nidal Hasan, the Army psychiatrist and al-Qaida sympathizer who carried out a mass shooting at Fort Hood in 2009, killing 13 people.
Under Army regulations, soldiers can keep personal firearms but are prohibited from bringing them onto military bases unless the weapons are registered. Army officials said Spc. Lopez had not registered his new pistol at Fort Hood.
Practically speaking, they acknowledged, there was little they could have done to prevent him from sneaking a weapon onto the sprawling Army post, where more than 50,000 people work each day. Although military police carry out random security checks, requiring everyone to pass through metal detectors would be "frankly untenable," said Army Col. Steven Warren, a Pentagon spokesman.
Fort Hood officials said Spc. Lopez opened fire about 4 p.m. local time. In the space of a few minutes, he shot soldiers in two buildings and kept shooting while in a moving vehicle. In addition to killing three soldiers, he wounded 16 others, three of them critically.
He was finally confronted by a female military police officer. Spc. Lopez at first raised his arms, but then reached for his pistol. The officer responded with gunfire as Spc. Lopez put the pistol to his head, killing himself, Army officials said.
Gen. Milley, the Fort Hood commander, said there was no indication that Spc. Lopez had come onto the base to hunt down specific targets. But he said investigators think the truck driver had gotten into a verbal altercation that may have prompted him to start shooting. "We're looking into that, trying to determine what the trigger event was," he said, adding that investigators were also examining whether Spc. Lopez had financial or marital problems.
Gen. Milley said he had no details about reports that Spc. Lopez was upset at having had little time to attend his mother's funeral last year. The commander also said it was "too early to tell" whether Spc. Lopez had received sufficient psychiatric help.
Gen. Ray Odierno, the Army chief of staff, described Spc. Lopez as "a very experienced soldier" who had served for nine years in the Puerto Rico National Guard before enlisting in the active-duty Army in 2010. While with the National Guard, he served a one-year deployment in Egypt's Sinai Peninsula. In 2011, after joining the Army full time, he served four months in Iraq and was one of the last U.S. troops to come home at the end of the war.
Mr. McHugh, the Army secretary, told lawmakers that Spc. Lopez had "a clean record" in terms of conduct. He said his personnel file had "no outstanding bad marks for any kinds of major misbehaviors that we're yet aware of." The Army released a summary of Spc. Lopez's service history, including awards and decorations, but did not provide detailed records or specific information about disciplinary proceedings.
Army leaders said there was no record that Spc. Lopez had been wounded or injured in Iraq. But they said he had "self-reported" a possible traumatic brain injury from his wartime service. He had recently been undergoing an evaluation to determine whether he suffered from post-traumatic stress disorder, Army officials said.
Spc. Lopez had been stationed at Fort Hood since February and was assigned to the 13th Sustainment Command (Expeditionary) as a truck driver. He had previously been stationed at another Texas base, Fort Bliss, for two years as an infantryman.
According to a person familiar with Spc. Lopez's military service, he had been taking medications while stationed at Fort Bliss to help with depression and anxiety, but his behavior did not raise any red flags. Because of privacy restrictions, his commanders were unaware of the medications he was receiving.
Spc. Lopez's mother had passed away last year, and he had been seeing a chaplain for counseling on that and other undisclosed issues, said the person familiar with the soldier's military record. The military monitors people for stress levels, and Spc. Lopez was deemed to be "low risk" at the time.
Defense Secretary Chuck Hagel said Thursday afternoon that the Pentagon will be looking for "any new lessons learned" from Wednesday's shooting. "We need to let investigators do their work and help us understand how this happened," he told reporters at a news conference that wrapped up a three-day summit of defense leaders from Asian nations in Honolulu.
After a mass shooting by a defense contractor at the Washington Navy Yard in September, Mr. Hagel ordered a series of security changes at military installations, including more rigorous screening of personnel, and creation of an analysis center to examine "insider threats." The Pentagon also pledged to adopt a other security measures after the 2009 Fort Hood shootings.
Mr. Hagel did not respond substantively when asked why the Defense Department had not fully implemented those recommendations. "Let me assure our country, the people who serve: We do take this seriously. We recognize the imperfections. Obviously, something went wrong," he said.