Thousand Oaks gunman went from Marine vet to mass shooter. Investigators want to know why.

02:20 - Source: CNN
California gunman was known to police
CNN —  

Authorities have identified a Facebook post believed to have been made by the gunman who killed 12 people at a bar in California, a law enforcement official said.

Authorities say Ian Long, 28, fired a Glock .45-caliber handgun without a word as patrons line-danced at the Borderline Bar & Grill in Thousand Oaks late Wednesday night. He first shot a security guard and a woman working at the counter, but authorities say there was no indication he was targeting employees.

Hours after Long was found dead, apparently from a self-inflicted gunshot wound, police searched for clues at the home where he lived with his mother.

00:45 - Source: CNN
Witness: I heard 18 to 20 rounds at a time

Latest developments

•From young Marine to a gunman. Long served in the Marines for nearly five years as a military machine gunner and was deployed to Afghanistan, Defense Department records show.

Police were called to his home in April for reports of a disturbance and a crisis team felt he might be suffering from post-traumatic stress disorder, but they ultimately cleared him.

Long’s mother “lived in fear” of what her son might do, a neighbor says. She was concerned about Long, the neighbor said, but she was not worried about her own safety.

•Hundreds of people gathered to mourn the victims. “Tonight we are a hurting city but we are a community of love, of compassion and of unity,” Thousand Oaks Mayor Andy Fox said at a vigil Thursday night. “We are also a community of hope.”

•Authorities have not named all of the victims, but CNN has independently identified some of them.