The call came in around 5 p.m. Monday for flames showing from the St. Francis of Assisi School, which is located on Saxer Avenue.
Chopper 6 was overhead as plumes of heavy smoke billowed from the roof of the building.
Chopper 6 over school fire in Delaware County
Firefighters knocked down the bulk of the fire but remained on the scene Monday night to extinguish any hotspots.
The school was founded in 1929 and serves students from Pre-K to 8th grade.
"At this time, the fire appears controlled to one building. All classes at the school will be cancelled for at least tomorrow. Efforts are already underway to locate an alternate learning location for those who will be affected by the loss of classroom space," said a spokesperson for the Archdiocese of Philadelphia in a statement.
The damaged building houses grades Pre-K, Kindergarten, Grade 1, and Grade 3. Students in grades 2 and 4 through 8 attend classes in another building on the campus.
The principal told Action News that roughly 150 students have been affected.
Hundreds of people came out well into the night in total disbelief.
"I was just so surprised. It was really devastating," said 7th grader Sam Trevea.
"This is really sad for me because like a lot of people have a lot of memories here," added 4th grader Lizzie Smith.
This tight-knit community is confident they'll get through this together.
"I think of everyone stays positive and faith in God. Everything's going to work out OK," said Kevin Ferry of Springfield Twp.
No injuries have been reported.
The cause of the fire remains under investigation.