A boiler room explosion at an East Mount Airy public school critically injured a maintenance employee and forced the evacuation of the building, officials said Wednesday.

The incident happened about 1:30 p.m. at Edmonds School, 8025 Thouron Ave. Fernando Gallard, a spokesman for the Philadelphia School District, said that a school employee who had been working on the boiler was taken to Einstein Medical Center.

Students at the K-5 school were evacuated to a nearby building for a time, but ultimately returned to Edmonds. They will be out of school for two days while repairs are made to the boiler, Gallard said.

The worker, whose name was not released, was in stable condition at Einstein Medical Center on Wednesday night. - Kristen A. Graham