LOS ANGELES (AP) — SpaceX engineers are investigating the cause of Saturday's failed flight of the Falcon 1, a low-cost, light-lift rocket developed by the Southern California-based company.

SpaceX CEO Elon Musk said in a news release that a problem occurred causing the rocket's two stages to remain together instead of separating after the launch from a Central Pacific atoll. However, he described the launch, powered by the company's new Merlin engine, as "picture-perfect."

SpaceX is developing the single-engine Falcon 1, the nine-engine Falcon 9, the 27-engine Heavy Falcon and the Dragon cargo-crew capsule to fly to the international space station when the current space shuttle fleet retires in 2010.