OAKLAND (CBS SF/BCN) — A Victorian possibly occupied by squatters erupted into a 3-alarm fire late Tuesday night that left the building gutted and two nearby residences slightly damage, Oakland fire officials said.

Oakland Fire Battalion Chief James Bowron said crews responded to 911 calls of a fire in a vacant 3-story Victorian in the 800 block of 20th St. at around 9 p.m.

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“Crews arrived on scene to find this 3-story Victorian with heavy fire on the first and second floor with exposure to houses,” he said.

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Firefighters quickly elevated the response to three alarms in the densely populated neighborhood. The Victorian was heavily involved that personnel inside the burning building were pulled out.

The attack by some 50 personnel at the scene was refocused on the exterior and trying to prevent its spread to adjacent buildings.

Firefighters believe squatters inside the Victorian may have sparked the fire.

“Talking to some of the neighbors it does sound like there may have been some squatters inside the building,” Bowron said. “It is tough to investigate (for a cause) since the structure is so heavily damaged.”

No injuries were reported and the fire was under control by early Wednesday. Two buildings on each side of the Victorian suffered minor damage.

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“We made an aggressive attack interior attack to the point we had to get drawn out of the main fire building, but there was minimal damage to the exposures,” Bowron said.