Thirteen people have died, including a gunman and a sheriff’s sergeant, after a mass shooting at a California bar popular with college students, police said.

Officers were called to Borderline Bar & Grill in Thousand Oaks, near Los Angeles, at around 11.20pm local time.

A police officer, described as a sheriff’s sergeant, and the gunman are among the 13 confirmed to have died. The gunman died inside the bar, police said on Thursday.

There was no update on the motives of the gunman, how they died, or whether the person acted alone.

Borderline, which bills itself as the “biggest dance floor in town,” had been hosting an event called “College Country Night” when the shooting occurred.

A witness told KABC-TV that there were many young people “having a great time” in the bar when a man entered and “started shooting.”

The witness, who escaped unharmed with his stepson, said he saw the gunman shoot multiple people.

One officer said it had been “quite some time” since there was a shooting of any kind in Thousand Oaks.

The city of about 130,000 people is around 40 miles (64km) west of Los Angeles.