MOJAVE, Calif. - An explosion killed two people and critically injured four others at a Mojave Desert airport site used by the pioneering aerospace company that sent the first private manned rocket into space, authorities said.
The blast at a Mojave Air and Space Port facility belonging to Scaled Composites LLC also left some toxic material, said Kern County fire Capt. Doug Johnston.
Scaled is the Mojave-based builder of SpaceShipOne, the first private manned rocket to reach space, and is developing a successor for the new space tourism business Virgin Galactic.
Aerospace designer Burt Rutan, who heads Scaled, told The Associated Press he had no information and was heading to the scene.
Video news helicopters showed wrecked equipment and vehicles at the airport in the high desert north of Los Angeles near Edwards Air Force Base. The blast site was in a remote unpaved section of the airport.
The accident involved nitrous oxide, but it was not known if an actual rocket motor test was under way or whether it occurred during preparation for a test, fire Inspector Tony Diffenbaugh told KABC-TV.
The blast site was in a remote unpaved area. Scaled uses nitrous oxide as an oxidizer in its rockets, which are tested at the airport. An oxidizer provides the oxygen that rocket fuel needs to burn. Scaled's Web site notes that "temperatures and pressures must be carefully controlled'' during oxidizer transfers.
Kern County fire crews and bomb experts were headed to the scene, where there was concern that airport personnel could be exposed to hazardous materials, said sheriff's Deputy Vince Martinez.
Paramedics reported two people were killed, four were critically injured and one suffered minor injuries, said Mark Corum, a spokesman for Hall Ambulance Service. The injured were airlifted to Kern Medical Center about 70 kilometres from the airport, he said.
A call seeking comment from the airport manager was not immediately returned.
The Mojave airport is where the Rutan-designed Voyager aircraft was built. It made history in 1986 when it achieved the first nonstop flight around the world without refueling.
In 2004, Rutan's SpaceShipOne, funded by Microsoft co-founder Paul Allen, made the first privately financed manned spaceflight by climbing more than 100 kilometres high on a suborbital journey above Mojave. SpaceShipOne went on to make two more flights to win the US$10 million Ansari X Prize.
Rutan has since been developing SpaceShipTwo for entrepreneur Richard Branson's Virgin Galactic, which plans to offer $200,000 rides into space for tourists.
Aerospace and defense contractor Northrop Grumman Corp. owns 40 percent of Scaled and recently agreed to acquire the rest of it. The deal is awaiting regulatory approval and should close next month.
Northrop Grumman spokesman Dan McClain said the company had no comment on the explosion.
The airport is an important part of Mojave, an unincorporated community of about 4,000 people, said Bill Deaver, publisher of weekly Mojave Desert News. It employs about 1,500 people, he said, and is the country's first inland spaceport certified by the Federal Aviation Administration.
The airport is often crowded with parked airliners that are not in service. Its flight operations often involve unusual aircraft undergoing testing, and civilian test pilots undergo training there.
The airport has been a popular location for movie and television production. Part of "Speed'' was filmed at the airport -- a Boeing 707 was blown up in a scene that was supposed to be Los Angeles International Airport.
