Los Angeles ? A powerful storm plowed through California on Monday, producing heavy rain that collapsed a school roof and forced hundreds to flee homes in an area devastated by recent wildfires.

Power failures caused by the weather blacked out about 20,000 homes and businesses around the state. Two traffic deaths were linked to the storm.

At higher elevations, heavy snow in a mountain pass east of Los Angeles closed the main route connecting Las Vegas to Southern California. North of the city, the main route to San Francisco was snarled by snow that forced the state Highway Patrol to shepherd motorists over another pass in caravans.

The rain apparently collapsed the roof of a classroom at the North Orange County Regional Occupational Program building in Anaheim. Seven people were taken to a hospital, said police Sgt. Rick Martinez. Their conditions were not immediately available.

Roughly 150 students were at the center, which prepares high school students and adults for medical occupations, said spokeswoman Pat Hansmeyer. Only three of the students were minors, and they were not injured, she said.