Thirteen people are dead after a shooting at a bar in the Los Angeles-area suburb of Thousand Oaks.
The gunman, identified as 28-year-old David Ian Long, walked up to the building, shot a security guard, stepped inside, shot several employees, and opened fire inside the bar, Ventura County Sheriff Geoff Dean said.
Long also fired at police officers when they arrived, killing a deputy sheriff identified as Sgt. Ron Helus, Dean told reporters on Thursday morning. Helus died in a hospital.
Read more: Colleagues say Helus 'died a hero'
Long, the shooter, was a 28-year-old veteran of the US Marine Corps. He used a Glock 21 .45-caliber handgun, Dean said.
Authorities believe he shot himself. They have not found a motive.
Up to 15 other people were injured and taken to hospitals, Dean added. The names and identities of the victims have not been released.
Read more: What we know about the Thousand Oaks shooter
The shooting began about 11:20 p.m. PT at the bar, which is in Thousand Oaks, a suburb about 45 miles northwest of Los Angeles.
The gunman had been "down with a gunshot wound" when officers entered the building, Dean said, adding that there was "blood everywhere."
Some witnesses described seeing a smoke grenade go off, but Dean said officers did not find any such devices in the bar.
Video footage showed police officers standing outside the bar for up to an hour after their initial arrival. Other footage showed civilians carrying out injured people from the bar and tending to them.
Officers from the FBI Joint Terrorism Task Force and the Bureau of Alcohol, Tobacco, Firearms and Explosives went to the scene.
Jeremy Childs, a reporter with the local Ventura County Star newspaper, tweeted a picture of a 19-year-old bar patron who had bloodied his hands throwing a chair through the window in an attempt to escape the building during the shooting.
The bar was having a college night, which appeared to have attracted a young crowd. The bar is near California Lutheran University and several other schools.
Read more: There were reportedly survivors of the Las Vegas shooting at the Thousand Oaks shooting
A Pepperdine University spokesman said in a statement that several of its students were in the bar but did not specify their conditions.
The Los Angeles KTLA reporter Eric Spillman reported that classes at California Lutheran had been canceled because of the shooting.
"My heart aches to learn about the horrific shooting in Thousand Oaks on college night," Sen. Kamala Harris tweeted on Thursday morning. "Praying for the injured and the families of those killed who, like so many others, have lost their loved ones to gun violence. Leaders in Congress must act — not some day, but now."
President Donald Trump mourned the loss of life on Twitter and joined Harris in praising what he called "great bravery shown by police."
"California Highway Patrol was on scene within 3 minutes, with first officer to enter shot numerous times," Trump said of the slain officer, Helus.
Trump also ordered that the US flag be flown at half-staff at the White House and all public and military buildings until Saturday evening.
