A classroom wing of Bolsa Grande High School in Garden Grove was damaged Sunday afternoon in a three-alarm fire.
About 60 firefighters fought the blaze, which was reported at 1:15 p.m. and contained in about an hour, said Jeff Spargur, division operations chief at the Garden Grove Fire Department.
Spargur said two classrooms were extensively damaged and another six sustained smoke and water damage. Although there were some students at the Westminster Avenue campus, the wing was empty when the fire broke out.
One firefighter was treated at a local hospital for minor injuries and is expected to be released tonight, Spargur said.
The fire's cause is under investigation.