EL SOBRANTE -- A fire that charred a middle school in El Sobrante causing millions of dollars in damage Saturday morning has left school officials wondering how to accommodate students and employees Monday when the bell rings.

Some workers and students at Juan Crespi Middle School will have to find alternative buildings to use since some rooms are unusable, Contra Costa County Fire Protection District fire Chief Keith Richter said today.

"It is pretty well damaged," Richter said.

The three-alarm fire apparently started in the business office area and spread to the roof. Administrative offices and classrooms were damaged. Officers said the office was fully involved when they arrived and then it spread to the attic.

The damage at the school, located at 1121 Allview Ave., is probably several million dollars, according to Richter.

Some 48 firefighters battled the blaze with chainsaws and hoses. They also pulled the ceiling from the inside of the structure.

"It took a lot of resources to make sure that we got everything," Richter said.

The fire was in the concealed spaces above the ceiling of the single-story building, which made fighting the blaze challenging.

Firefighters were expected to be at the school in unincorporated Contra Costa County until at least the afternoon to inspect the concealed roof spaces.

The official cause of the fire hasn't been determined but arson has not been ruled out, Richter said.

The fire was contained at 6:43 a.m., about 1.5 hours after it started. Someone called 911 at 5:17 a.m. to report the fire.