The Philadelphia Police Department has launched an investigation into the fatal shooting of an unarmed driver by an officer during a traffic stop. Commissioner Richard Ross said Wednesday the officer was on foot when he attempted to pull over 52-year-old Richard Ferretti in a minivan. Ferretti refused to stop and attempted to drive off, trapping the officer “between the car and some other area where he didn’t feel like he could escape,” Ross said. The officer fired his weapon and the van struck several cars before stopping. No weapon was found in the vehicle, according to investigators. Police said they had received several calls from college students in the area concerned about the van circling the block several times. In a separate incident late Tuesday, police shot and wounded a man after officers said he refused to put down a gun.