MOJAVE, Calif. (AP) — A Virgin Galactic space tourism rocket exploded after taking off on a test flight in Southern California's Mojave Desert, a witness said Friday.

At least one was dead and another was injured, California Highway Patrol said. The SpaceShipTwo rocket is typically flown by a crew of two pilots and has been under development at Mojave Air and Space Port in the desert northeast of Los Angeles.

"During the test, the vehicle suffered a serious anomaly resulting in the loss of SpaceShipTwo," Virgin Galactic tweeted Friday.

Ken Brown, a photographer who witnessed the crash, said the space tourism craft exploded after it was released from a plane that carries it to a high altitude.

The company founded by British billionaire Richard Branson would not say what happened other that it was working with authorities to determine the cause of the "accident."

Virgin Galactic has been the front-runner in the fledgling space-tourism industry.

SpaceShipTwo was designed to be carried aloft by a specially designed jet and then released before igniting its rocket for suborbital thrill ride into space and then a return to Earth as a glider.

Virgin Galactic, once it finished developing its rocket ship, was going to launch space tourism flights from the quarter-billion-dollar Spaceport America in southern New Mexico.