The fire was reported around 8 p.m. at Lindenwold School 4 on the 900 block of Gibbsboro Road in Lindenwold, Camden County.
Firefighters arrived to find smoke coming from the roof of the building.
According to Superintendent Dr. Kristin P. O'Neil, evening facilities staff members and a construction crew were at the school when the fire started. No injuries were reported.
O'Neil said crews were still assessing the situation.
The cause of the fire remains under investigation.