PLEASANTON -- Students hoping to break in new school clothes and parents eager to remember their child's first day of school were disappointed this morning when classes were canceled at the last minute at Hearst Elementary in Pleasanton.

The discovery of mold in several classrooms on Monday evening forced the district to close the school this morning to clean up the fungi. Classes for the rest of the Pleasanton school district started as scheduled.

Hearst principal Mike Kuhfal sent an e-mail to parents Monday, informing them that mold had been found on the walls in classrooms in the C building.

According to the e-mail, the plan was to move those classes elsewhere on campus. But further testing later on Monday uncovered mold in four additional buildings, said district coordinator Myla Grasso.