MOJAVE, Calif. (AP) — Federal accident investigators have arrived in California to begin a probe into the cause of an accident that destroyed a prototype space tourism rocket ship during a test flight.

More than a dozen investigators in a range of specialties are forming teams to examine the crash site in the Mojave Desert, collect data and interview witnesses.

At a news conference today, the acting chairman of the National Transportation Safety Board, Christopher Hart, said he didn't know yet whether Virgin Galactic's SpaceShipTwo had flight recorders or the altitude of the accident.

One pilot was killed and another injured when the spacecraft broke up yesterday after being released from a carrier aircraft at high altitude. The accident scattered debris over a wide area of uninhabited desert.

The flight was the 55th for SpaceShipTwo but only the fourth to include a brief rocket firing.

Virgin Galactic founder Richard Branson told reporters at Mojave Air and Space Port, where the winged spacecraft was under development, that he's determined to find out what went wrong.