By ALYSSA NEWCOMB, JACK DATE, MIKE LEVINE and PIERRE THOMAS
The soldier who allegedly went on a deadly shooting rampage at Fort Hood today was identified as Spc. Ivan Lopez, according to law enforcement officials.
Lt. Gen. Mark Milley did not identify Lopez at an evening news conference, but said the alleged shooter arrived at Ft. Hood, in Killeen, Texas, in February from another installation.
The alleged shooter was on medication, was receiving treatment for depression and anxiety, and was being evaluated for possible post-traumatic stress disorder, Milley added.
"He was not diagnosed as of today with PTSD. He was undergoing a diagnosis process," Milley said.
"There are reports that he self-reported a traumatic brain injury."
Milley added that the alleged gunman was married with a family and served a four-month tour of duty in Iraq in 2011. He was not believed to have been wounded in action.
Law enforcement sources told ABC News Lopez, 34, was among the four people -- all soldiers -- who died in the shooting at the Army base.
"Respondents at the scene engaged the shooter and the shooter is dead from a self-inflicted gunshot wound," Milley said.
At least 16 other service members were injured in the shooting and were being treated at area hospitals.
"Obviously, we are digging deep into his background," Milley said of the shooter, noting that the probe included the suspect's psychiatric history and experiences in combat.
Lopez was an active duty soldier and served as a truck driver in the 1st Infantry Division, sources said. He also served in the National Guard from 1999 until 2010.
Milley declined to discuss a possible motive, though he said the incident was not believed tied to terrorism.
Fort Hood was the site of a mass shooting in 2009, when Army psychiatrist Maj. Nidal Hasan killed 13 people.
During Hasan's trial, he called himself a "mujahedeen," or Muslim holy warrior, and did not deny he was the shooter. He was convicted and received the death penalty in August 2013.