A marijuana grow operation was discovered Wednesday morning inside a commercial building in Boyle Heights where a fire burned for 54 minutes before being extinguished by firefighters.

Crews arrived at 3529 E. Olympic Blvd. at 2:40 a.m. and found fire burning through the roof of the 50-foot-by-50-foot building. Firefighters made their way inside and encountered heavy smoke with very little visibility, according to Margaret Stewart of the Los Angeles Fire Department.

Firefighters discovered a marijuana grow operation in the building and a large air conditioning unit had fallen through the roof, Stewart said.

A department HazMat team was sent to the scene due to the discovery of bottles of unknown chemicals and gases inside the building, she said.

A total of 93 firefighters extinguished the flames in 54 minutes and a knockdown was called at 3:34 a.m., Stewart said.

No injuries were reported. Arson investigators were called to the scene per department protocol.

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