About 04:45 PST, all four occupants of a Beech Bonanza were killed when the airplane struck high terrain near Chino. The flight had originated at Corona, Calif., enroute to Lake Tahoe. The Chino airport reported visual conditions and a 1,100-foot overcast at the time of the accident. Radar data showed a target that initially headed west, turned north, and then made a 360-degree turn to the left. The initial recorded altitude of the target was 900 feet mean sea level (msl) and the last recorded altitude was 2,400 feet msl. The terrain around the crash site showed extensive fire damage. Preliminary examination of the wreckage indicated that the airplane struck the ground while in cruise configuration with the engine producing power.