PHILADELPHIA (AP) -- Police are investigating the fatal shooting of a 23-year-old man in West Philadelphia early Sunday. Authorities say the unidentified man was shot once in the chest on Dewey Street at about 2:53 a.m. He was pronounced dead at the scene. TV station WPVI reports that the victim got into a dispute with a 25-year-old armed security guard who was double parked on the same block. The victim reportedly parked behind the security guard to drop something off to his girlfriend, and when he returned to his car an argument ensued. Homicide detectives are conducting interviews, but no charges have been filed.