<p>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.<br /><br />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.</p>
<p>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.<br /><br />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.</p>