PHILADELPHIA - Three Philadelphia police officers were ambushed by gunfire while responding to a shooting Wednesday night in Northeast Philadelphia, authorities said. Police were called to a property on the 7500 block of Whitaker Avenue around 7 p.m. after investigators say a 12-year-old boy reported to police that his father had shot his uncle. Investigators say a father and his juvenile son were arguing when the boy's uncle stepped in and began to argue with the father. Police believe the father fired a shot inside the house that caused the boy and his uncle to retreat upstairs.