At least three people have died in an explosion at a Los Angeles County Sheriff’s Department’s training facility.

The explosion was reported on Friday around 7.30am (12.30am Saturday morning AEST) at the Biscailuz Training Facility, Los Angeles County Sheriff’s Department spokesperson Nicole Nishida said.

Tragically, she said, three members of the department died.

The explosion happened at a facility located just under 10 kilometres east of downtown LA, which houses the sheriff’s department’s special enforcement units and bomb squad.

The incident is believed to have been an accident, but remains under investigation.

It’s unclear whether the incident was related to a training session or whether officers were handling evidence, the source said.

Attorney General Pam Bondi in a post on X said it “appears to be a horrific incident.” She said federal agents are at the scene to learn more.

“Please pray for the families of the sheriff’s deputies killed,” Bondi wrote.

California Gov. Gavin Newsom’s office said he’s been briefed and that the Governor’s Office of Emergency Services is in contact with the Sheriff’s Department and closely monitoring the situation.

The FBI is responding to assist with the incident, according to the FBI’s Los Angeles field office.

Agents with the Bureau of Alcohol, Tobacco, Firearms and Explosives are also on scene, according to Bondi.

The work of the bomb squad is complicated by the fact officers have to ensure no other explosive material that could be stored there is vulnerable to detonation, the senior law enforcement source told CNN.

“I am heartbroken to hear of the terrible tragedy that has unfolded today at an L.A. County Sheriff’s Department facility,” Los Angeles County Board of Supervisors Chair Kathryn Barger said in a statement.

“I am closely tracking the situation as we learn more about what occurred and the condition of those affected. My heart is heavy, and my thoughts are with the brave men and women of the Sheriff’s Department during this difficult time. We stand with them and their families as they navigate the hours and days ahead,” Barger said.

Aerial footage from KABC-TV shows the explosion happened in a parking lot filled with sheriff patrol cars and box trucks.