The soldier who killed four and wounded 16 at the Fort Hood military base had been seen by an Army psychiatrist last month and was being treated for depression, Army leaders said Thursday.
Army Secretary John McHugh said the shooter had a "clean record" and there were no indications he was at risk for violent behavior.
"So the plan forward was to just continue to monitor and treat him as deemed appropriate," he said.
McHugh told lawmakers the shooter was undergoing "a variety of treatment and diagnoses for mental health conditions ranging from depression and anxiety to some sleep disturbance."
He was prescribed "a number of drugs to address those, including Ambien," McHugh said.
Fort Hood commander Mark A. Milley revealed the gunmen's name at an afternoon hearing Thursday, identifying him as 34-year-old Spc. Ivan Lopez.
McHugh said he had served two deployments — in the Sinai region as part of the Army National Guard in Puerto Rico, and another for four months as a truck driver in Iraq from August to December 2011.
McHugh said his records showed no wounds, no direct involvement in combat, and no record of a Purple Heart or any injury that would have led the Army to further investigate for a traumatic brain injury.
McHugh said the shooter first enlisted in the U.S. Army in June 2008 as an infantry soldier, and later reenlisted as a truck driver.
He and his wife are both from Puerto Rico, and lived outside of the base, McHugh said. His wife was being questioned Wednesday night, he said.
Lawmakers expressed concern over whether other soldiers facing mental health issues are receiving the treatment they need.
"There are other young men and women who have these issues ... we obviously have to get to the bottom of this," said Sen. Jack ReedJack ReedDems introduce MAR-A-LAGO Act to publish visitor logs Senators demand Pentagon action after nude photo scandal Mattis on defense budget boost: 'America can afford survival' MORE (D-R.I.).
McHugh pledged that the Army would work with lawmakers to provide the facts as they learn them so that they could conduct oversight.
Army Secretary Gen. Raymond Odierno said security procedures put in place after the 2009 Fort Hood shooting by Maj. Nidal Hasan helped to mitigate damage.
"I would just say that I believe that some of the procedures that have been put in place four and a half years ago, did help us yesterday," Odierno said.
The shooter's alleged weapon, a .45-caliber handgun, was not registered on the Army base as required, since the Army cannot compel soldiers who live off the base to register their weapons, McHugh said.
"We try to do everything we can to encourage soldiers to register their personal weapons," said McHugh. "We are not legally able to compel them to register weapons when they reside off-post."
Army investigators have not yet found any involvement with extremist organization of any kind, but it will continue to be looked at, McHugh said.
"We're going to keep an open mind," McHugh said. "We will go where the facts lead us."
The White House said President Obama had been briefed about the latest developments on the attack on Thursday morning and would continue to receive updates throughout the day.
Obama first learned of the shooting during a fundraiser Wednesday afternoon at a Chicago steakhouse. The White House said counterterrorism czar Lisa Monaco provided him with updates during the event.
Asked about military support for veterans suffering from psychological illness, White House press secretary Jay Carney said he wanted to separate that discussion from the shooting at Fort Hood, where facts remained unknown.
But, Carney said Obama was "committed to upholding our sacred trust with our veterans" and had requested "historic levels of support" in his budget proposals.
“After a decade of war, we need to be very mindful in this country that even as those wars end, what we owe our veterans does not end," Carney said. "The president has been very mindful of this."
Carney declined to say whether the president would visit Fort Hood during his trip to Texas next week.
Justin Sink contributed.
— This story was updated at 9:30 p.m.