A gunman has opened fire in a crowded Southern California bar popular with college students, killing 12 people including a sheriff's deputy, in the latest US mass shooting.
The gunman, identified by authorities as Ian David Long, 28, was found dead in the office of the Borderline Bar and Grill, located in Thousand Oaks, about 64 km northwest of Los Angeles, apparently having shot himself.
Ventura County Sheriff Geoff Dean told a news conference that Long had apparently fired at random with a .45-calibre Glock handgun with an extra-capacity magazine. There was no known motive, he said.
Long was in the Marine Corps from 2008 to 2013, reaching the rank of corporal, and served as a machine gunner who was deployed to Afghanistan for eight months. Dean said it was possible that Long had suffered from post-traumatic stress disorder.
He said officers had gone to Long's home in nearby Newbury Park, in April to answer a disturbance call and found him to be agitated. Mental health specialists talked with Long and determined that no further action was necessary.
The bar shooting was the latest mass killing in the United States and was sure to revive the debate on gun control.
Less than two weeks ago 11 worshippers at a synagogue in Pittsburgh were killed by a man shouting "All Jews must die."
Bar patron Cole Knapp, 19, said he saw the gunman walk in and stop at the counter, apparently paying a cover charge. Then Knapp heard gunfire and saw a young woman at the counter shot repeatedly.
"It took a couple of seconds for people to realise what was going on and once that happened it was just utter chaos," he said.
Knapp said he first helped people hide behind a pool table and then fled to the bar's outdoor smoking patio, where people were unaware of the shooting.
Once outside, Knapp said, he and a friend helped carry a gunshot victim to an ambulance.
Thousand Oaks, with a population of about 127,000, is a leafy, sprawling suburb named the third safest city in the United States for 2018.
"I've learned it doesn't matter what community you're in," Dean told reporters when asked if he was surprised this happened in Thousand Oaks. "It doesn't matter how safe your community is. It can happen anywhere."
Names of the victims were not immediately made public and about 60 people were gathered at a teen centre in Thousand Oaks waiting to learn if their loved ones were among the dead. After families were briefed, one man sat outside on the curb sobbing loudly.
Ventura County Sheriff's Office Sergeant Ron Helus, a 29-year veteran with a wife and son, was shot in the bar and died at a hospital.
A procession of at least 50 police cars and other vehicles escorted the hearse carrying his body from the hospital.
US President Donald Trump, who has resisted a surge in calls for tougher gun control measures since 17 students and staff were shot dead at Stoneman Douglas High School in Florida earlier this year, ordered flags to be flown at half-staff at public buildings and grounds.
© AP 2018