Officers responded to a non-specific bomb threat at Arthur L. Johnson High School shortly after dismissal, Clark police said.
As students were already leaving for the day, all after school activities were canceled, police said.
Along with police, the Union County Sheriff's Office Canine Unit responded to the school for a search of the building, police said.
The bomb threat is currently under investigation by the Clark Police Juvenile Bureau, police said.
School will be open a delayed opening bell schedule due to New Jersey Graduation Proficiency Assessment testing, police said.
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