3 dead, 16 injured at Fort Hood: 'We do not know a motive'

3 dead, 16 injured at Fort Hood: 'We do not know a motive' »Play Video
Lt. Gen. Mark Milley

FORT HOOD, Texas - Three people were killed and 16 injured in the attack before the suspected gunman - identified by military sources as 34-year-old Ivan Lopez - apparently turned his weapon on himself.

"He walked into one of the unit buildings, opened fire, got in a vehicle, fired from vehicle, got out walked into another building and opened fire again," Lt. Gen. Mark Milley said.

"We do not know a motive," he said. "Soldier had behavior and mental health issues and was being treated for that."

Lopez was also undergoing diagnostic testing for post traumatic stress disorder.

Officials say in 2011, he served 4 months in Iraq.

"You never know who you live next door to," said Xanderia Morris, who said she was with the wife of the suspected gunman when she heard the tragic news.

"She wasn't able to say anything, she just broke down," Morris said. "She was hurting and in disbelief."

This is the second time in recent years that Fort Hood has been the scene of a mass shooting.

In 2009, Major Nidal Hassan opened fire at Fort Hood, killing 13 and injuring at least 30.