The shooting at the Borderline Bar and Grill in Thousand Oaks has claimed the lives of 12 people and the gunman, Ventura County Sheriff's deputies say.
Among them was Sergeat Ron Helus, a 29-year veteran of the force, who died overnight at Las Robles hospital.
The 54-year-old had been nearing retirement, and was one of the first to enter the bar to confront the shooter.
Helus was shot multiple times.
At a press conference, Ventura County Sheriff Geoff Dean said that "There's no doubt that they saved lives by going in there and engaging with the suspect."
Helus is survived by his wife and adult son.
A procession will be transporting his body from the hospital to the Ventura County Medical Examiner's office.
