Three Los Angeles County Sheriff’s deputies were killed in a blast at a compound that houses the agency’s arson and explosive unit on Friday morning.

The explosion at the Biscailuz Center Academy Training facility in East Los Angeles resulted in the department’s worst loss of life in a single event since 1857. 

The officers were identified as Detective Joshua Kelley-Eklund, Detective Victor Lemus and Detective William Osborn, all of whom were assigned to the Special Enforcement Bureau’s Arson Explosives Detail.

The fallen members — whose elite unit responds to 1,000 calls yearly — were longtime veterans who had been on the job for 19, 22 and 33 years, respectively.

The three were remembered as heroes by the county’s top cop.

“There are no words to express the pain and sorrow we feel,” Sheriff Robert Luna said late Friday night. “These heroes represented the best of our Department, exemplifying courage, integrity, and selfless service. This is not only a heartbreaking loss for their families, but for all of us.”

At an earlier press briefing, he said they were “fantastic experts and, unfortunately, I lost three of them today.”

It’s unclear what sparked the deadly blast, though investigators are preliminarily looking at a possible training accident, a person briefed on the matter told the Associated Press.

Aerial footage from local news helicopters showed the explosion happened in a parking lot where patrol cars and box trucks were parked.

No other injuries were reported, and the scene was deemed safe about four hours after the explosion.

“There is currently an investigation going on to determine what happened from the very beginning to the end,” Luna said. “I know everybody wants answers, please understand we just rendered the scene safe.”

The tragedy is the worst loss of life that the department has faced from a single incident since 1857 when four officers were shot and killed, Luna said.

“I have met with two of three families thus far,” Luna said of the deputies’ loved ones. “Those were extremely challenging conversations.” 

The department’s homicide detectives with help from the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosive will probe the scene.

“We lost three lives, and we want to make sure what happened,” Luna added. “We don’t want a repeat for this.”

A deputy who is part of the sheriff’s SWAT team called the trio of deputies “the best of the best.”

“When you sign up for the job, you know it’s going to be a dangerous job. As the years goes on, you realize how dangerous it is,” said Jason Zavala.

US Attorney General Pam Bondi said she had spoken to Luna, as well as US Attorney Bill Essayli, to provide federal assistance.

“We have FBI and [Bureau of Alcohol, Tobacco, Firearms and Explosives] agents on the ground to support,” she said in an X post.

“Please pray for the entire Los Angeles County Sheriff’s Department.”

California Gov. Gavin Newsom called the incident a “heartbreaking day for California.”

“Three members of the [Los Angeles Sheriff’s Department] lost their lives in the line of duty – serving with courage and honor,” Newsom said in a tweet.

“Jennifer and I are holding their families and the entire Los Angeles County Sheriff’s Department in our hearts. We will never forget their service to our communities.”

With Post wires