Marshfield police say two fireworks-mortar shells taped to P-V-C pipe caused Thursday’s bomb scare. Nobody was injured and there were no explosions.  The device was found in the front yard of a home and the resident called police.  An investigation found what is being called a suspicious device.  P-V-C piping had been taped together with two-inch fireworks mortars and they were aimed at the house.  The Marathon County Bomb Squad deployed and X-rayed the device.  Charring indicated one or more of the mortars may have ignited, but no damage was done.  Police say they have a person of interest in the case, but no names have been released.