SOUTH GATE, Calif. (AP) — An explosion during police training in Southern California left two officers with serious burns.

South Gate police Capt. Darren Arakawa says one officer from his department and another from the Downey Police Department were hospitalized with significant burns to their upper bodies after the explosion during routine K-9 training exercises at a commercial building in South Gate.

Police have not said what caused the explosion that happened shortly before 6 p.m. Wednesday.

Several departments were involved in the training.