Piles of debris were actually once part of the roof at the Selzer School.
Fierce winds from the storm have forced the building to shut down.
"It looked like a war zone. It was incredible to see all the damage that had occurred here at Selzer School," said Emanuele Triggiano, Dumont Schools Superintendent.
Cleaning crews have spent half the weekend handling dust from debris, broken windows, leaking from the roof, and water in the ventilation equipment.
Most of the damage is confined to the middle school section, making 12 of its classrooms unfit for use.
6th, 7th, and 8th graders will not be able to use the classrooms again for at least two weeks.
"We'll have to decide whether or not we can take care of the 6th, 7th, and 8th grade students, provide them with a strong educational program, and one of the things we're obviously going to need is the cooperation of all the parents.
A very large downed tree in the middle of the street leading to the school also complicates access to the building.
This was the only school building in Dumont with such serious damage, but between blocked roadways and the lack of power to some homes, the whole school district had the day off Monday.
"[The children] they should be prepared for change. We're going to have to make adjustments and I know they will be able to do that because they always cooperate with me," said James Kennedy, PhD, Selzer School Principal.
All Dumont Public Schools will be closed on Tuesday, March 16 due to residual storm damage as well.
All schools are expected to be re-opened on Wednesday, March 17.