Witnesses observed an aircraft fly over the city of Enterprise, Oregon on a bright night with clear sky conditions. Reportedly, the aircraft was flying very erratic; and just as it disappeared from the witnesses' sight, an explosion and fireball were observed where it disappeared. According to one witness, the aircraft appeared to maneuver up and then drop down before it crashed. The plane crashed on down sloping terrain in a nose low, right wing down attitude. The plane slid about 100 ft down hill and the wreckage was destroyed by fire. The propeller separated during impact and showed evidence of power; it was badly bent and had large gouge marks on the tips. The flight control cables were complete and unbroken to the tail and were continuous to both wings except where the wings had separated. A toxicological check of the pilot's blood revealed an alcohol level of 0.449%. The elevation of the crash site was about 3900 ft MSL.