The Army says it has good reason to believe that unstable mental health is the reason Spc. Ivan Lopez shot 19 people at the Fort Hood base in Texas on Wednesday. Three died and 16 were wounded in the rampage.
"We have very strong evidence that he had a medical history that indicates unstable psychiatric or psychological condition. We believe that to be a fundamental, underlying cause," Lt. Gen. Mark Milley, senior officer at Fort Hood, explained.
Army investigators are also looking into an argument that Lopez had with another service member before the attack, but Army officials told lawmakers they had no reason to believe that Lopez would harm anyone.
"We had no indication on the record of that examination that there was any sign of likely violence either to himself or to others, no suicidal ideation," Army Secretary John McHugh told a congressional hearing.
Investigators don't believe Lopez targeted specific soldiers during his attack, and they don't believe he had any ties to potential terrorists, although they have not ruled out that possibility.
Neighbors have expressed shock over the shooting.
"I saw him at lunch," neighbor Shaneice Adams said. "He seemed perfectly fine. It was just mind-blowing, really."
Churches in the area say it's a lot for the community to deal with just five years after the previous shooting at Fort Hood and a little over 20 years since the massacre at Luby's Cafeteria in Killeen.
Dr. Randy Wallace, pastor at First Baptist Church in Killeen, told CBN News that this week's shooting is taking a toll on people in the area.
"It re-opens the Ft. Hood massacre," he said. "We had a number of our civilians that worked in the room where the Fort Hood massacre took place. Five years is not very long to be processing witnessing a mass murder."
Wallace re-wrote this Sunday's sermon after Wednesday's shooting. His new focus is Romans 8.
"The corruption of this world doesn't challenge the power of God," he said, "and the corruption of this world doesn't separate us from the love of God."
It's a powerful message for thousands at Fort Hood and in Killeen, struggling to find comfort and hope.