PAUL J. WEBER, Associated Press
WILL WEISSERT, Associated Press

FORT HOOD, Texas (AP) — Authorities say the gunman who opened fire at Fort Hood, killing three people and himself, was an Iraq War veteran being treated for mental illness.

Wednesday’s attack also wounded 16 people at the Texas military base, where a 2009 shooting rampage killed 13 people and wounded more than 30.

A federal law enforcement official says investigators will interview the gunman’s wife, search his home, and examine whether his combat experience caused lingering psychological trauma.

The official, who spoke to The Associated Press on condition of anonymity, says investigators also must find witnesses who know what the shooter said and did during the attack.

Fort Hood’s senior officer, Lt. Gen. Mark Milley, says the gunman had sought help for depression and anxiety, and was being assessed for post-traumatic stress disorder.