At least 12 people have been killed, including a police officer, at a country music 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.
Officials say the suspect, who has not been identified, was found dead inside.
They have not yet confirmed any motive for the shooting.
How did the shooting occur?
A college country music night was under way when the suspect, apparently dressed in black, entered the bar and opened fire.
Reports say the suspect may have used smoke grenades and at least one weapon, described as a semi-automatic handgun by witnesses.
A injured man told local television channel KTLA: “We just dropped to the ground, we heard a lot of screaming. My friend is the DJ so she cut off the music, we just heard a lot of mayhem.”