SOUTH PHILADELPHIA (WPVI) -- Police say a National Park Service ranger shot and killed a dog which attacked him in South Philadelphia.It happened on the grounds of the Gloria Dei (Old Swedes') Church at Washington Avenue and South Water Street 1 a.m. Friday.The ranger was performing a routine check of the property when he approached a homeless man and woman near a wall surrounding the church.Police say the couple's dog suddenly lunged, biting the ranger in the leg.The ranger opened fire, killing the dog.The ranger was taken to Thomas Jefferson University Hospital to be treated for his leg injury.Police say the couple told them the dog was not restrained when the incident happened.----------