A small plane designed for high-speed aerobatics crashed near San Francisco Tuesday, killing two people, investigators said. The single-engine Glasair III exploded on impact when it crashed into a field near Discovery Bay in Contra Costa County. The Federal Aviation Administration said the pilot and one other person died in the crash. The plane was registered to DSB Inc., a company in Nevada. The Glasair III is a kit aircraft capable of reaching 300 miles per hour and is designed for aerobatics, KGO-TV in San Francisco said. Steve Pease, a farmer who was in the area, told KGO the plane\'s engine seemed to sputter. He ran to the scene where the plane was engulfed in flames. \"That was it,\" said Pease. \"A lot of black smoke and a ball of flames.\"