MANTUA — The discovery of an undetonated explosive device on the grounds of a South Jersey school made for some tense moments on Thursday.

Police said said the principal of the Gloucester County Christian School found an unexploded military ordnance in the woods near the school. School was not in session and the remaining students in after-school programs and staff were evacuated, according to police.

After the device was examined by bomb squads from Gloucester and Camden counties and the EOD unit from the base, it was determined it was too unstable to be moved and should be detonated where it was found, according to police.

Police said they will search the grounds again on Friday for any other possible devices.

The school, which has students from kindergarten through 12th grade, is located on Golf Club Road on the site of the former Nike missile base, according to the school's website.

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