THOUSAND OAKS, Cali. (WCJB) -- At least 13 people were killed and perhaps a dozen others injured late Wednesday at a packed Southern California bar when a gunman dressed in black burst in, tossed smoke grenades and fired off dozens of rounds, witnesses and authorities said.
The suspect was found dead inside the bar, police said. Authorities are working to determine who he is and what his motive may have been.
Sgt. Ron Helus was among the dozen killed, according to the Ventura County Sheriff's Department.
As one of the first on scene, Helus was fired on multiple times. He was rushed to a hospital, where he succumbed to his injuries.
Initial reports from officers from the Ventura County Sheriff's Department and California Highway Patrol said about 30 shots were fired. Hundreds were inside the bar at the time.
Police said they responded to the Borderline Bar and Grill in Thousand Oaks, California, about 40 miles west of Los Angeles, just before midnight local time after multiple shots were fired.
The gunman used a semi-automatic weapon in the attack, according to the Ventura County Star.
The number of potential victims is unclear, but a witness told ABC Los Angeles station KABC-TV that he saw a security guard get shot, and that the alleged shooter appeared to use "a big handgun" and smoke grenades.
"The gunman was throwing smoke grenades all over the place," a different witness told KABC. "I saw him point to the back of the cash register ... and he just kept firing. I ran out the front door.
"There was probably three or four [shots]. I hit the ground. I look up -- the security guard is dead. Well, I don't want to say he was dead, but he was shot. He was down."
The bar is a country-themed bar known for its large dance floor and live music events, according to its website.
"With over 2,500 square feet of wide open dance floor, Borderline has provided a haven for country line dancing folks of all ages equipped with pool tables," the website said. "Over the years, Borderline has hosted many legendary performances such as The Beach Boys, John Rich, Collin Raye, Mark Chesnutt, Lee Brice, Adam Carolla & Tyler Farr to name a few."
This is a breaking story. Please check back for updates. ABC News' Will Gretsky and Bonnie Mclean contributed reporting.