A passenger rocket plane developed by Virgin Galactic crashed after explosion on Friday during a test flight over California, killing one of the pilots and seriously injuring the other.

The suborbital vehicle was undergoing its first powered test flight over the Mojave Desert, about 150 km north of Los Angeles.

The vehicle known as SpaceShipTwo was slung beneath a carrier plane for takeoff from the Mojave Air and Space Port at about 9:20 a.m. (1620 GMT). When the paired planes reached a height of about 50,000 feet (15,240 meters) about 40 minutes later, SpaceShipTwo was released for the test.

"During the test, the vehicle suffered a serious anomaly resulting in the loss of the vehicle," Virgin Galactic said in a statement.

There was an explosion about two minutes after SpaceShipTwo dropped away from the carrier aircraft and fired the rocket engine.

Two pilots were on board. At least one parachute was reportedly sighted.

The California Highway Patrol confirmed to a local media that one pilot was dead and the other had suffered major injuries in the accident. The survivor was flown to hospital by air ambulance.

"Space is hard and today was a tough day," George Whitesides, the CEO of Virgin Galactic, told a news conference.

The carrier aircraft, WhiteKnightTwo, landed safely, said the British commercial company.

The flight marked the first use of a new type of fuel to power the ship's engine. Virgin Galactic switched SpaceShipTwo's fuel mixture from a rubber-based compound to a plastic-based mix and hopes that the new formulation would boost the hybrid rocket engine's performance.

Kevin Mickey, president of Mojave-based Scaled Composites, said that the engines using the new type of fuel had been thoroughly tested on the ground. Scaled Composites has played a key role in developing and testing SpaceShipTwo for Virgin Galactic.

The US Federal Aviation Administration said it was also investigating the crash. National Transportation Safety Board investigators were on their way to the site.

SpaceShipTwo, which has been under development at Mojave Air and Space Port in the desert northeast of Los Angeles, is designed to carry two pilots and six passengers on trips about 100 km above the Earth -- the beginning of outer space, where the tourists would be able to experience weightlessness. Tickets cost 250,000 US dollars each.

Virgin Galactic had planned to start such trips as early as next year.

The crash was the second catastrophe in the commercial space industry in a week. On Tuesday night, an unmanned rocket operated by private US firm Orbital Sciences Corp. exploded seconds after its launch.