Dredger-operator working to clean up a bush-laden area in the city’s Amager district yesterday got a serious shock when he heard a loud bang.The blast came from a sawn-off shotgun – one of two the dredger had inadvertently dug up, along with some compatible shells in a plastic bag. Police suspect the guns may belong to the Hells Angels motorcycle gang, whose clubhouse is just around the corner from the site.The items have been handed over to the police’s forensic unit.