Police are responding to reports of a mass shooting at bar in Thousand Oaks, California.
Police said at least six people, including one officer, were injured when gunfire broke out the Borderline Bar and Grill at about 11.20pm local time on Wednesday.
It is not yet clear if there were any fatalities.
Footage broadcast on local media showed people being carried away from the scene, apparently with bullet wounds.
Police said they were still working to get the scene under control. They could not yet confirm if the suspect was on the loose.
The bar was hosting a college country music night on Wednesday, according to its website.
Witnesses who were at the bar described a scene of panic.
Reports said the suspect may have used smoke grenades as well as a gun in the attack.