No one was hurt during the fire that lasted for 20 minutes because there were no classes.
The fire started at the Grade 6 classroom and spread to two neighboring classrooms occupied by Grade 4 and Kindergarten pupils.
At least P2 million worth of property, which included chairs, books and other school materials, was destroyed, said Fire Officer 1 John Brian Cabahug of the Medellin fire station.
Medellin mayor Ricky Ramirez said he was disappointed school officials failed to make sure that appliances were unplugged before they went home.
He will meet with school officials on Monday to decide where to temporarily accommodate the affected pupils.
Ramirez also had the classrooms demolished since one side of the school’s wall collapsed during the fire.