What was supposed to be relatively safe testing routine for the rocket motor of SpaceShipTwo went awry as a freak accident caused an explosion that took the lives of three people and injured three others.

The accident took place around 2:30 pm last Thursday, in the Mojave Air and Space Port facility in California. Three unnamed personnel were killed, while three others were critically injured. All suffered severe shrapnel wounds, with two of the three people who perished dying at the scene, while another died in the hospital.

Burt Rutan, aerospace designer and one of the founders of Scaled Composites, claimed that they were performing a completely safe testing of nitrous oxide flow through an injector for SpaceShipTwo's rocket motor, when the accident happened.  "We were doing a test we believe was safe. We don't know why it exploded. We just don't know," he said.

The victims of the accident were employees of Scaled Composites, a privately-owned space travel outfit run by Rutan. The rockets were proposed to be used in Richard Branson's Virgin Galactic space venture.

Virgin Galactic's president, Will Whitehorn, would not comment on the accident but instead gave the company's sympathy to the bereaved. Stuart Witt, the Mojave airport's general manager, acknowledged the dangers that come with space exploration. What we do is inherently risky," he said. "These are not the days we look forward to, but we deal with it."

Rutan's first manned Rocket, the award-winning SpaceShipOne, was the first of its kind to reach space and was privately financed by Microsoft co-founder Paul Allen. Rutan's current project, the SpaceShipTwo, has Virgin Galactic's Branson as one of its investors, with investments amounting to at least US$ 202 million. It was planned to be ready within a year, and have its commercial launch in 2009.