A SpaceX rocket exploded in midair during a test flight, though no one was injured, as the company seeks to develop a spacecraft that can return to Earth and be used again.
The rocket was a three-engine version of the F9R test vehicle that succeeds SpaceX's Grasshopper prototype.
"During the flight, an anomaly was detected in the vehicle and the flight termination system automatically terminated the mission," the company said in a statement, released on Friday.
"Throughout the test and subsequent flight termination, the vehicle remained in the designated flight area."
SpaceX noted that a Federal Aviation Administration representative was present during the test.
It stressed that the test was "particularly complex, pushing the limits of the vehicle further than any previous test."
The company plans to review flight record details to understand what caused the problem before conducting another test.
SpaceX is competing with other companies -- including Boeing, Sierra Nevada and Blue Origin -- to be the first commercial outfit to take astronauts to space, possibly as early as 2017.
Until then, the world's astronauts must rely on Russian Soyuz spacecraft at a cost of $70 million per seat.