LAFD said there were small explosions up to 2 a.m. Saturday from Friday night's controlled burn, but none since then. Investigators are waiting for the structure to burn down, and fully burn out before entering.

Fire crews had a busy evening putting out a controlled burn that had gotten out of control Tuesday. Around 6:26 p.m., the Concord Volunteer Fire Department was dispatched for a controlled burn that had reportedly gotten out of hand.

Officials said evidence was found of chemicals used to produce fireworks, prompting the decision to do a controlled burn to remedy the situation.