MONTCLAIR, N.J. (CBSNewYork) — An elementary school in Montclair, N.J. was evacuated Monday afternoon, after a student brought a relic grenade into the building.

Montclair police told CBS 2 the inert grenade was found inside the Charles H. Bullock School, at 55 Washington St. in Montclair.

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School principal Nami Kuwabara issued a letter to parents following the incident, explaining that students had been evacuated at 2:30 p.m.

A teacher had brought the relic grenade to Kuwabara’s office after a student brought it to the school, the letter said. Kuwabara notified police, who ordered school officials to evacuate the building.

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Following investigation, Kuwabara wrote, “the bomb squad determined that it was a ‘training/dummy device,’ securely removed it from the building and gave us the all clear to come back in to prepare for dismissal.”

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Students and staff responded quickly to orders to evacuate, Kuwabara wrote.