Police in California have said at least 12 people have died, and several others injured, following a mass shooting outside a bar in the Los Angeles suburb of Thousand Oaks crowded with students from nearby California Lutheran University.

Captain Garo Kuredjian of the Ventura County Sheriff's Department said the suspected shooter was "contained" at the scene, a country & western themed restaurant known as the Borderline Bar and Grill, while CNN reported the suspect was shot by police. One of the victims, the Sheriff's office said, was 29-year veteran Sergeant Ron Helus, who was due to retire next year. Witnesses report several shots being fired and smoke bombs lobed into the crowd of more than 200 patrons 40 miles northwest of Los Angeles as students attended a "college country night" celebration celebration.

"When deputies arrived they heard shots being fired, it was an active shooter situation," said Ventura County Sheriff's spokesman Eric Buschow. "They entered the location and I can tell you there are multiple fatalities, multiple injuries, among the victims is one of our sheriff's deputies that responded in that initial call, as well as the shooter."

An Emergency Information Hotline to assist locating people that may have been involved in the #BorderLineShooting incident has been established by @Venturaoes: at 805-465-6650

— Ventura Co. Sheriff (@VENTURASHERIFF) November 8, 2018

"It's a horrific scene in there," Ventura County Sheriff Geoff Dean told reporters Thursday. "There is blood everywhere." 

Police did not release any details related to the suspected shooter, although witnesses described him as having "light skin" and carrying a short-barreled semi automatic pistol attached to a large magazine.