Fresno Fire Department officials tell Action News the fire started in a corner of the lab on Wednesday evening, causing extensive damage to the room. The rest of the building suffered smoke damage as well.
One custodian was reportedly treated for smoke inhalation and school officials said the room would likely need extensive repairs before it could be used for classes. The cause of the fire was not immediately clear.
"There's so much damage in there right now, they're looking for the origin of the fire. It just appears that it started in the corner of the classroom. In that area, there was quite a bit of paper. It's under investigation right now," Capt. Tim Fulmer of the Fresno Fire Department said.
"We're in the process of assessing the usability of the classrooms. It's very likely that we'll have to relocate all of the classes that are in the C Building, temporarily until we can address the smoke damage in the building," Kelly Avants of the Clovis Unified School District said.
The school is working to figure out where the students will hold classes that normally would be held in the building.
Avants says by the time school starts Thursday there will be a plan in place.