Battalion Chief Mark Basque said the fire apparently started in an overloaded electrical circuit in a bedroom of a ground-floor apartment at 1277 Yulupa Ave.
One of the occupants smelled smoke or saw flames and called the fire department at 5:45 a.m. All the occupants of the building escaped safely and there were no injuries, Basque said.
The first unit arrived in three minutes but the ground-floor apartment was already well involved in flames, Basque said.
Twenty-nine firefighters responded and controlled the blaze in 30 minutes, Basque said.
The downstairs unit was destroyed and the other three apartments sustained moderate to heavy smoke damage, Basque said. The fire caused $150,000 in damage, Basque said.
The American Red Cross is helping the families find housing, Basque said.