The head of the federal agency examining last week's fatal crash of a Virgin Galactic passenger spaceship during a test flight in California's Mojave Desert said on Sunday the vehicle appears to have broken apart in flight.
"The debris field indicates an in-flight breakup," Christopher Hart, acting chairman of the National Transportation Safety Board, told Reuters during a interview.
"We'll know that for certainty when we look at all the sources we have," he said.
The NTSB is leading the investigation into Friday's crash of SpaceShipTwo, which was undergoing its first powered test flight since January when it crashed, spreading debris over a 5-mile (8 kilometers) swath of the Mojave Desert north of Los Angeles.
One pilot was killed and another was badly injured.
Preliminary data gathered in the Virgin accident indicates that a structural failure, and not an engine explosion, led to the crash, according to a report published Sunday in the Wall Street Journal.
Citing a source familiar with the nascent investigation, the report said video and early data was focusing on "aerodynamic forces" that could have led to its downing.
Virgin Galactic's owner, British billionaire and entrepreneur Richard Branson, traveled to Mojave on Saturday to meet with his team and NTSB investigators.
He said he was determined to uncover the cause of the crash and said he believed the dream of space tourism for everyday passengers would live on.