The fire started when a chemistry experiment went wrong, according to officials with Clovis Unified Schools. The chemicals used in the experiment are not known at this time.
According to the Fresno Fire Department, five or six students are being treated for burn injuries. At least one student's hair was singed.
The classroom was evacuated and students are being kept out of the class until it can be aired out.
Stay with Action News and ABC30.com for more on this story.