SAN JOSE (CBS SF) — A massive 2-alarm fire roared through an abandoned commercial building in San Jose early Wednesday, completely gutting the structure before the flames were brought under control.

San Jose fire officials said crews responded to multiple calls reporting the blaze in the building located at Bascom Ave. at Forest Ave. near O’Connor Hospital at around 2:20 a.m.

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“Our first arriving unit reported that they had an abandoned building that was boarded up and had a chain-link fence around it fully involved with basically fire coming out of every opening,” said San Jose Fire Capt. Brad Cloutier.

Initially, crews did not know if anyone may have been inside the structure which once was an office building surrounded by a parking lot.

“Their first job is to make sure if there is anyone in the building, they are out,” Cloutier said. “They had no survivable conditions inside so they started their fire attack.”

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The immediate concern was the fire spreading to nearby homes, so firefighters aggressively fought the massive flames on the backside of the building.

The intensity of the blaze forced firefighters on the defensive. As more crews arrived with the blaze being elevated to a second alarm, they surrounded the burning building and began dumping hundreds of gallons of water on the fire.

“We’re going to be here for a quite a while,” Cloutier said.

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Cause of the fire remained under investigation. Cloutier said arson investigators would likely be part of the investigation since there was a small fire at the site on Tuesday.