A Cape Cod elementary school was briefly evacuated Wednesday after an 8-year-old boy brought an inert grenade to school for show and tell.

The third-grader told his teacher at the Ezra Baker School the grenade was in his backpack, but told her it was a toy. School principal Kevin Depin tells the Cape Cod Times school officials didn't believe it was dangerous but called town police and fire departments as a precaution.

Dennis police Captain William Monahan says the device was a World War Two era grenade from which the explosive charge and detonator had been removed. It was turned over to the state police bomb squad for disposal.

He says police are treating it as "an innocent mistake on the part of a little boy."