"Sergeant [Ron Helus] was on the force for 29 years, was looking to retire in the next year or so and has survived by his wife and son", Sheriff Dean said.
Police say at least 10 people are known to have been injured and others are self-reporting with injuries at local hospitals.
"I have nothing to believe there is any terrorism link but we will certainly look at that option", he said.
Holden Harrah, who was at the bar, told CNN the gunman walked in and opened fire within seconds.
More than a dozen people have been killed, including a sheriff's deputy, in a shooting at a bar filled with college students in Thousand Oaks. "And that's what's really blowing my mind, it's a really safe area".
Initial reports indicated that a man had opened fire with a semi-automatic gun at about 11.20pm.
Some had to use chairs to break windows inside the bar to escape. Shooting began at 11:20pm, where around 200 people were inside the country music venue.
Officers said at least 30 shots had been fired and that victims would be at multiple locations as they fled. The western-style bar hosts theme nights such as country, salsa and swing dancing.
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Borderline, which bills itself as the "biggest dance floor in town", had been hosting an event called "College Country Night" when the shooting occurred.
"He went in there to save lives. I ran out the front door".
There was no screaming, she said.
"I think everyone was in so much of a shock that it was sheer panic", Whittler said.
Nick Steinwender, student body president at nearby California Lutheran University, rushed to the scene when he heard about a shooting at the bar where he knew friends and fellow students were.
He was interviewed by police at his home in April after an episode of agitated behaviour that they were told might be post-traumatic stress disorder. People were trying to get out the window.... "I know we don't have all the details in yet, but you know, it just feels like it's an attack on our community".
Kuredjian said it has been "quite some time" since there was a shooting of any kind in Thousand Oaks, a city of about 130,000 people about 64 kilometres west of Los Angeles, just across the county line.