A three-alarm fire was reported Wednesday night in the multipurpose room at Sierra Vista Elementary School in Clovis, fire officials said.
Someone alerted fire officials around 8 p.m. after they saw smoke coming from the school at 510 Barstow Ave., just west of Clovis Avenue, as they were walking by, said Clovis Deputy Fire Chief John Binaski.
Nobody was inside the school at the time. The fire was under the stage in the school's multipurpose room, which was being renovated.
Binaski said the building likely would have been a complete loss without the quick action of the passerby.
About 40 firefighters from Clovis, Fresno and Cal Fire responded to put out the blaze. No one was injured and the cause is under investigation.
Clovis police closed both Pollasky and Barstow avenues west of Clovis Avenue to traffic for a time due to the fire.