What turned out to be a malfunction of an automated lockdown system brought a fleet of police to Northern Valley Regional High School's Old Tappan campus on Thursday, authorities said.
Administrators and two Class III special law enforcement officers assigned to the school quickly determined that the activation was accidental, Old Tappan Police Chief Thomas M. Shine said.
The lockdown was lifted and the day's activities resumed, he said.
School officials were investigating.
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