UPDATE: Fire in Walnut Creek Office Building Started in Attic

The fire that broke out in a San Miguel office building Wednesday night caused an estimated $225,000 in damage and appeared to have started accidentally in a mechanical space in the attic, fire officials said Thursday.  

The fire started about 8:04 p.m. Wednesday in the two-story building in the 1800 block of San Miguel Road, at the top of Newell Hill Place. Contra Costa Fire Protection District Battalion Chief Ben Smith and Fire Marshal Lewis Broschard said firefighters saw heavy smoke and flames shooting as high as 20 feet in the air when firefighters arrived at 8:10 p.m. 

A total of 34 firefighters brought the two-alarm fire under control within about 30 minutes, Smith and Broschard said. No injuries were reported, and it's not known if anyone was in the building at the time of the fire, Smith said. The fire didn't spread to buildings or homes nearby. 

Walnut Creek police closed San Miguel Road between Sierra Drive and Newell Avenue to through traffic but allowed residents  to get to their homes. 

Broschard said the cause of the fire is under investigation, though the "initial investigation revealed no suspected arson or "malicious" activity.  The fire in the shingle-sided building started in the attic and was not detected until flames burned through the walls and were visible from the street.

Broschard said the fire caused about $200,000 in damage to the building and $25,000 in damage to contents.  The complex has several medical offices listed at its address.

This is the third fire in three days in Walnut Creek.

On Monday just before 8 a.m., a transformer at an East Bay Municipal Utility District pumping station at Geary Road and Putnam Boulevard exploded and sent a plume of smoke over the city. The fire was quickly extinguished and no injuries or disruption of service were reported. 

About 2:15 p.m. Monday, a fire, apparently caused by grease on a grill, sent flames shooting up to the ceiling at Buckhorn Grill in downtown's Plaza Escuela. Employees and customers safely left the restaurant as smoke began billowing out of the Locust Street restaurant.