No children were in the building when the blaze broke out in a classroom at the Ringwood Avenue school shortly before 7 a.m. and was quickly extinguished, responders said.
It caused a significant amount of smoke damage in the building, they said. A cause wasn't immediately disclosed.
Mutual aid responders included firefighters from Ringwood, Pompton Lakes, Bloomingdale and Oakland, as well as local police and EMS.
Both the Haskell and Wanaque elementary schools were closed as a result. Before and after care, as well as school activities, were all cancelled.
A Tuesday night Board of Education meeting was moved to the Wanaque School. It begins at 7 p.m.
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