An investigation is being held into the death of a couple who were killed when their plane exploded in Sutter County, California. Donald and Adeline Dennehey were flying over Yuba City in a Zodiac aircraft when the plane crashed into a prune orchard. According to witnesses, the two-seater plane, which was being piloted by Donald Dennehey, was making sputtering noises before it exploded with a bang and fell to the ground in pieces. The National Transportation Safety Board is leading the investigation.