A mass shooting Wednesday night in the city of Thousand Oaks in Southern California, has left 13 people dead including an officer and a gunman, and at least 11 injured, local authorities said.

　　Police vehicles line a road in the vicinity of a shooting in Thousand Oaks, California, early Thursday, Nov. 8, 2018. [Photo: AP]

　　Ventura County Sheriff Geoff Dean told the press that deputies responded to multiple reports of gunshots fired at Borderline Bar and Grill around 11:30 p.m. local time (0730 GMT, Thursday).

　　Deputy Sgt. Ron Helus went into the bar with another highway patrol officer. Helus was shot several times in confrontation with the shooter and died in hospital later, Dean said.

　　According to witnesses at the scene, the shooter threw a smoke grenade into the bar before opening fire with a handgun.

　　Madison Cummings, an eyewitness at the bar, told Xinhua that the shooter had a beard and short black hair, wore all black and held a black handgun.

　　"At the first sight, I thought it was a joke, because the music did not stop. But later I smelled the gun fire, then I knew it's real," she said.

　　"We immediately ducked down, freaking out," she said. As soon as the shooter was outside her eyesight, Cummings got up and went up to the door.

　　She sat in her car parked in front of the bar for 45 minutes until the cops walked the patrons to a safe place.

　　Helus was a 29-year veteran who was set to retire next year.

　　"Ron was a hardworking, dedicated sheriff's sergeant. He was totally committed, he gave his all and tonight, as I told his wife, he died a hero. He went in to save lives, to save other people," Dean said, choking up.

　　He said the identification and the motive of the shooter remain unknown, and it is unclear whether the shooting was terrorism related.

　　This is the second deadly mass shooting within two weeks in the United States. At least 11 people were killed and six others injured after a gunman opened fire inside a synagogue in Pittsburgh, Pennsylvania on Oct. 27.

　　According to a study released in August by the Institute for Health Metrics and Evaluation at the University of Washington, the United States has one of the highest gun-related death tolls in the world due to lax gun control laws.