PETALUMA (CBS SF) — A fire burned at a commercial building in downtown Petaluma overnight, causing significant damage, fire officials said.

The Petaluma Fire Department said the fire broke out at about 3:44 a.m. on the 120 block of Keller Street. Firefighters arrived to find smoke coming from the first and second floors of the two-story building.

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Crews using a ladder truck forced entry into the building and found the fire burning in one of the building’s businesses on the first floor. The fire was quickly extinguished and confined to one unit, the fire department said.

No one was found inside the building at the time of the fire, which was brought under control at 4:18 a.m. The entire building sustained significant smoke damage, and the city’s Building Department “red-tagged” the entire building with businesses to remain closed for an unknown period, the fire department.

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There were no fire alarms or fire sprinkler system because of the age of the building. There was no word on what caused the fire and the department credited a passerby headed to work who noticed the fire and called 9-1-1. Had it not been for the passerby’s 9-1-1 call, the fire would have spread to other commercial buildings, the fire department said.

Total damage to the building was estimated at $300,000. No firefighters were injured.

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