Multiple people have been shot after a gunman opened fire in a bar in Thousand Oaks, California.
Initial reports indicated that a man had opened fire with a semi-automatic gun at about 11.20pm.
Officers on the scene said at least 30 shots had been fired and that victims would be at multiple locations as they fled, local media reported.
The suspect has been described as a Middle Eastern man in his early 20s wearing all black clothing and with a beard.
Witnesses say a man fired several shots from a handgun before throwing smoke bombs into the crowded bar in southern California.
Police reported that a California Highway Patrol officer had engaged a suspect.
One officer is reported to be injured, according to local media.
Ventura County Fire Department said there was an "ongoing active shooter incident" reported at Borderline bar and grill.
A trail of blood was visible on the street at the entrance of the venue.
Pictures and video footage show firefighters and first responders flooding the scene after multiple injuries were reported.
A police helicopter swirled overhead and officers surrounded the area with cars.
The suspect was initially reported to be inside the bar.
Officers later reported a man matching the suspect's description on the ground at the scene outside a window.
They said that soon after the gunman opened fire, victims were running to a nearby petrol station to get help.
Officers escorted large groups of people to safety as they left the area.
The extent of the victim's injuries has not yet been released.
Social media reports claim the suspect shot the bouncer before throwing a smoke grenade and firing more shots.
It is reported to be "college night" at the bar, with some suggesting the attack was aimed at university students.
The bar is located about 40 miles west of Los Angeles and describes itself as a western-style bar with a spacious dance floor used for theme nights such as country, salsa and swing.
Authorities have urged the public to avoid the area and that roads are being blocked.
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