PICO-ROBERTSON (CBSLA) — Firefighters battled a blaze at a commercial structure in the Pico-Robertson area of Los Angeles for more than two hours Friday afternoon, a blaze arson investigators believe might have been related to a possible illegal marijuana grow in the building.

Fire crews Friday battled a greater alarm blaze at a commercial structure in the Pico-Robertson area of Los Angeles. (CSBLA)

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According to the Los Angeles Fire Department, the fire broke out at about 11:32 a.m. in the 9000 block of West Pico Boulevard.

The building, at the corner of Pico Boulevard and Crescent Avenue, was said to be a former synagogue that had been converted to a commercial building with a few businesses operating inside.

“It’s very sad to see this building go up in flames,” Shimon Ram, a witness, said. “We used to pray there and stuff.”

An elderly couple living in a single-family home behind the building were said to be unharmed after sheltering in the dwelling with first responders while crews battled the blaze.

When fire crews initially arrived on scene, they began breaking through doors and windows in an effort to locate the source of the flames.

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But, less than half an hour later, crews had to take a defensive position — exiting the building and coming down from the roof — due to the heavy flames and difficulty making entry into the structure.

“There was zero visibility as they made entrance into the building on two different sides,” Dean Zipperman, LAFD assistant chief, said.

Fire crews used tarps to protect cars parked near the building as they fought back flames. (CBSLA)

Additional firefighters were called to the scene around 12:30 p.m. to help tackle the blaze from the ground and from the rooftop of an adjacent building, as flames engulfed the second floor and attic — causing the roof to collapse.

At about 1:45 p.m., crews were working to hit the last remaining hot spots in the structure. One firefighter was taken to a nearby hospital with a non-life threatening heat-related illness.

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Arson investigators said they believe there might have been an illegal marijuana grow in the back of the building that could be related to the fire, though the cause was still under investigation.