A 50m safety cordon was put in place around a police station in Greater Manchester after a man walked in with a hand grenade.
The man found the ordinance during a clear-out of his house in Altrincham. He put it in his car and drove it to the police station on Barrington Road.
Officers warned nearby residents to take cover in the rear rooms of their homes at 1900 GMT on Friday.
A police bomb disposal unit made the device safe.