Updated 11:26 a.m. EST:  The gunman behind the mass shooting at a Southern California dance bar has been identified as 28-year-old Ian David Long. Long opened fire at the Borderline Bar & Grill in Thousand Oaks, which was crowded with more than 100 people, according to CBS  News, and killed 12 people including a sheriff’s sergeant who was responding to the shooting. Long was found dead inside the bar, possibly from a self-inflicted wound, according to the report. Authorities have yet to find a motive for the shooting. Long, who had served in the U.S. Marine Crosp, used a Glock .45-caliber handgun in the deadly shooting. He first shot a security guard outside the bar, before continuing his rampage upon entering establishment. Earlier: Another mass shooting has taken place in America, this time at a dance bar in Southern California where a gunman opened fire late Wednesday during “college night,” killing 12 people, including a sheriff’s sergeant. According to USA Today, the shooter, who reportedly was randomly firing at the Borderline Bar & Grill, also died during the massacre. Police say they have identified the gunman, but declined to reveal his name. Pepperdine University, which is nearby, said on Twitter that “multiple” students were at the bar during the incident. The bar is also a popular hangout spot for students from California Lutheran University and was also close to other universities including California State University Channel Islands in Camarillo and Moorpark College in Moorpark. The report notes that some people used bar stools to break the windows to try to escape the rampage.

“It’s a horrific scene in there,” Ventura County Sheriff Geoff Dean said at a news conference. “There’s blood everywhere.”

It is unclear how exactly the shooter died. Sheriff’s Sgt. Ron Helus was attempting to help when he was shot after entering the building. According to the report, Helus and a highway patrolman responded to multiple 911 calls when they arrived at the bar at 11:20 p.m. Upon hearing gunfire, they went inside. Helus was immediately struck multiple times, and died at a hospital. There were also “multiple other victims,” with various levels of injury, according to the sheriff, who described the shooting as a “tragic, tragic situation.”

The shooting, according to USA Today, is the deadliest in the United States since 17 students and teachers were killed in Parkland, Fla. back in February. It also comes less than two weeks after a gunman killed 11 worshippers in a synagogue in Pennsylvania.

Early Thursday morning President Donald Trump tweeted out that he was aware of the “terrible shooting.”