Twelve people, including a police officer, have been killed by a gunman at a bar in Thousand Oaks, California.
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.
How did the shooting happen?
Police say the suspect, Ian David Long, was dressed in black, and forced his way into the bar after shooting the bouncer.
A college country music night was under way when the suspect apparently threw a smoke grenade before opening fire, witnesses say.
Police say he used a legally-owned .45 calibre Glock semi-automatic handgun, which had an extended magazine that is illegal in the state of California.
The extended magazine allowed the gun to carry more than its typical 11-bullet capacity.
Police say they do not yet know how many shots were fired, or whether the gunman ever reloaded during the attack.
One witness, Teylor Whittler, who was celebrating her 21st birthday said: “I was on the dance floor and I heard the gunshots, so I looked back and then all of a sudden everyone screamed: Get Down!
“It was a huge panic, everyone got up, I was trampled, I was kind of left on the floor until some guy came behind me and grabbed me and dragged me out.”
People escaped the bar by using chairs to break windows, while others reportedly sheltered inside the venue’s toilets.