Update 2:52 p.m. Worcester Fire Company chief Dave Cornish said that a "smoke condition" was caused by an antifreeze spill in the school's mechanical room, and that the smoke set off the school's fire alarm.
Students have been allowed to go back inside the school after an evacuation that lasted about 30 minutes.
Fire companies from North Wales, Skippack, Towamencin, North Penn assisted Worcester Fire Company at the scene.
Initial story below.
A fire in the mechanical room of Worcester Elementary School caused the school to be evacuated shortly after 2:00 p.m. on Thursday.
Montgomery County Public Safety radio reports indicated that the fire was brought under control quickly, but that students remained outdoors as firefighters worked to clear smoke from inside the building.
This is a developing story.