The pipe burst overnight at Dickinson High School on Milltown Road.
Officials from the Red Clay School District decided at 6:30 a.m. to cancel classes. Early buses enroute to the school were turned around.
A spokeswoman told Action News 2 or 3 classrooms were damaged and would be out of service until repairs can be made.
The school was expected to reopen Thursday and operate on a normal schedule.
