"The school was placed in a 'shelter in place' status as officers responded," Police Chief James Powderly III said late Wednesday afternoon.
The body was found just before 11:45 a.m., Powderly said, adding that "foul play is not suspected."
School officials quickly sent a robo-message to parents, the chief said.
"Students and staff were assembled in the auditorium, where they were briefed by both school and police administrators," Powderly said. "Counselors were made available to students following the briefing.
"Police provided assistance during a regularly scheduled school dismissal" at 2 p.m., the chief added.
Classes were expected to begin as usual on Thursday.
An autopsy by the Bergen County Medical Examiner's Office will officially determine the cause of death.
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