Three deputies with the Los Angeles County Sheriff’s Department were killed Friday morning when a powerful explosion occurred at the department’s training center.

The incident occurred around 7:30 a.m. local time at the Biscailuz Training Academy facility. So far, the cause of the explosion has not been clarified, while the details of the victims remain unknown. There is no official information on possible injured.

The explosion occurred in an area of the facility that houses the Special Operations Group and the Explosives Unit, which includes bomb squads. Sources who spoke to the Los Angeles Times said the explosion occurred while members of the team were handling or transporting explosives.

The surrounding area has been evacuated.

Attorney General Pam Bodie wrote on social media, “I just spoke with U.S. Attorney Bill Easily about the horrific incident that claimed the lives of at least three people at a security forces training facility in Los Angeles. Federal agents are already on the scene gathering information. Please pray for the families of the victims.”

In a later statement, she said she had also contacted the county sheriff, Robert Luna, and that FBI and ATF agents have already been deployed to the area.

A witness who was at the facility at the time of the explosion said he initially thought it was an earthquake, due to the force of the shockwave.