Shelby Township police are investigating two World War II grenades donated to the Salvation Army on Van Dyke Avenue at 23 Mile Road.
Police say a store employee found three hand grenades Monday afternoon that had been dropped off in a donation box over the weekend.
Police evacuated the Salvation Army and nearby businesses as a precaution.
The Michigan State Police Bomb Squad took the explosive devices to be properly disposed of, police say.
Police say there appears to be no criminal intent.
The area has been given the all-clear and the thrift store is back in business.