The Piper Cherokee went down in rough terrain at about 10: 50 am at a site about 8 km near the Livermore Municipal Airport. Ian Gregor, a US Federal Aviation Administration (FAA) spokesman, said the cause of the crash is still unknown.
FAA investigators are heading to the crash site and the National Transportation Safety Board is also planning to investigate, CBS 5 television quoted Gregor as saying.
Published 10 May 2010, 03:34 IST