Twelve people, including a police officer, have been killed by a gunman at a bar in Thousand Oaks, California.

Axar.az reports citing Western media that the shooting began at 23:20 local time on Wednesday about 40 miles (65km) north-west of Los Angeles, police say.

At least 200 people were reportedly inside the Borderline Bar and Grill, which was hosting a university student night, at the time of the attack.

Police have named the suspect as 28-year-old Ian David Long, who had suspected mental health issues.

Officials believe the US Marine Corps veteran and local resident took his own life inside the bar.