ANAHEIM, Calif. -- A fire on Wednesday morning damaged 10 classrooms at an Anaheim elementary school that was being renovated, but no one was hurt, authorities said.

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The blaze at Palm Lane Elementary at 1646 West Palm Lane was reported around 4 a.m., Anaheim police Sgt. William Jefferson said.

"This is a big one," a Metro Net dispatch supervisor said, adding that roughly 75 firefighters battled the third-alarm fire before it was knocked down.

The fire damaged 10 classrooms in one wing of a building that was under renovation, Anaheim fire spokeswoman Maria Sabol said. No injuries were reported, she added. A damage estimate was not immediately available.

Firefighters and equipment from the Garden Grove Fire Department were deployed in the firefighting effort, Sabol said.

Students of the school have been attending classes at a temporary school site during the school's renovation, fire officials said.

The cause of the fire was under investigation.