At approximately 1640 mountain time, a Piper PA-34-220T crashed during a visual approach to Madison County Airport. The pilot and his three passengers were killed. Witnesses said the airplane entered a left downwind for runway 17 but extended the downwind until it was three to four miles from the runway. It then flew base and final at a very low altitude. Witnesses said it was more than a mile from the runway at an altitude of 200 feet agl when, it suddenly rolled steeply to the right and made a descending turn into the terrain.