He said the gunman had a beard, wore a hat, had a black jacket and may have had glasses.
Ventura County Sheriff's Office Captain Garo Kuredjian said at a news conference tonight a sheriff's deputy was also shot and taken to a hospital.
SWAT teams have been pictured trying to surround the restaurant.
Officers escorted large groups of people to safety as they left the area.
Witnesses told The LA Times someone ran into the bar about 11.30pm, United States time, and started firing what appeared to be a black pistol.
People were hiding from the shooter in bathrooms and attic spaces, while others who managed to escape fled to nearby gas stations for medical help, reports claim. SKY2 was over the scene where a "College Country" night was being held, according to the bar's website.