Four people were injured Saturday afternoon in Atlantic City after a boat struck a submerged metal piling, the U.S. Coast Guard said. There were five people on the 24-foot Yamaha jetboat, including three children, when it crashed — ejecting three people from the boat, officials said. A man had serious injuries and was sent to AtlantiCare City Hospital. The boat struck the submerged metal piling outside of the channel near North Riverside Drive. The coast guard arrived on the scene with its 29-foot response boat with emergency medical staff to bring the five victims back to land safely, U.S. Co…