The gunman who killed 12 people in a Californian bar has been named as Ian David Long.
Ventura County Sheriff Geoff Dean named the suspect in a news conference, adding that Long had likely shot himself and that he was a veteran who had served in the U.S. Marine Corps.
Dean said Long appeared to have shot at random inside the club, using only a Glock .45-caliber handgun. There was no known motive, he said.
Paul Delacourt, assistant director in charge of the Los Angeles FBI, told a news conference that it was too early to speculate on the gunman's motives but that he appeared to have acted alone.
Dean detailed how his department had had several previous contacts with Long, including a call to his home in April, when deputies found him acting angrily and irrationally.
The sheriff added that a mental health crisis team was called at that time and concluded that Long did not need to be taken into custody.
One of the victims was a police officer.
Sergeant Ron Helus was a veteran officer of 29 years service and leaves behind a wife a son.
"It's a horrific scene in there. There's blood everywhere," Dean said in an earlier press conference.
The bar was identified as the Borderline Bar and Grill on Rolling Oaks Drive. Wednesday night's event was a 'College Country Night'.
Jeremy Childs, a local reporter with the Ventura County star, took this video of the aftermath.
Erica Sigman was in the bar when the shooting began.
"Shots rang out. We were hiding under the stools and there was like a little smoke bomb. My friend actually saw it, because I was under the stools with her. She saw the smoke bomb like start to go off, then you just heard everyone say, 'Run!"."
Sarah Rose-Desowen who was also at the scene said:
"I'm pretty sure I saw him (shooter) and like, I'll never get that picture out of my head but we dropped and we heard the gunshots, a lot of gunshots, a lot of gunshots."
Sheriff Dean, speaking on his last day before retirement, said he had been told 150 to 200 people were in the Borderline at the time and that "it could have been much, much worse."
Catherine Cheresh, who lives close to the bar, told Euronews what she heard.
“I heard the shots and thought it was gunfire but then thought “No. not here” and assumed it was a BB gun or something. Then I heard screaming. Sounded like teenagers and at first I thought it was laughing or yelling," she said.
"Then I heard sobbing. Someone yelled “Oh god. He just come in and shot up the place.” One of my neighbours was down there and we asked if he knew what was going on and he said 'Yeah someone shot up the bar.' It’s a line dancing place. It’s been in Thousand Oaks forever."
"Then there were sirens and more shots," Cheresh continued. "Someone yelled for everyone to head into the apartment complexes. He said get off the road, it isn’t safe to get inside the complex and off the street. Helicopters now. There was more yelling of 'Oh god oh god.' And more sirens. And that’s all I can hear. Is sirens and helicopters. It’s... I’m really scared."
Thousand Oaks is the second largest city in Ventura County, Southern California, part of Greater Los Angeles and around 64-kilometres from Downtown LA. The population is around 130,000.
An affluent city, average house prices are more than double the US average and the median household income is more than $120,000. A number of technology companies are based in the area and Thousand Oaks has been dubbed "the next Silicon Valley".
The city is a Republican stronghold in Ventura County and is home to California Lutheran University, a private, liberal arts college affiliated with the Evangelical Lutheran Church in America.
Thousand Oaks is ranked the fourth safest city of its size in the country, according to FBI crime reporting.
The borderline massacre was the fourth multiple shooting in the United States in less than two weeks.
The others included two women killed at a yoga class in Tallahassee, Florida, two people shot at a grocery in Jeffersontown, Kentucky, and 11 worshippers at a synagogue in Pittsburgh killed by a man shouting "All Jews must die."