R44 with four POB crashed at the AgLand Cooperative fertilizer plant. Images show (1) tail boom sliced by main rotor blades and (2) heavy damage to the front of the cabin and all occupants injured, with two treated locally at Avera St. Benedict Hospital and two with more serious injuries transferred to a more equipped medical center in Sioux Falls. The three pasengers were all AgLand employees. The location is very close to Parkston Municpal Airport