Authorities said a medical evacuation helicopter crashed in a Chicago suburb killing four people on board, AP reported. Police spokesman Sgt. Robb Wallers says the helicopter was headed for Children's Memorial Hospital in Chicago from another hospital just outside of the city. Wallers said the victims included three crew members and a patient. The helicopter belonged to Air Angels Inc., an emergency medical transport service. Wallers said the helicopter crashed in a field near a residential area in the suburb of Aurora and was engulfed in flames.