An unmanned SpaceX rocket broke apart shortly after liftoff early Sunday morning, NASA said.
"Something went wrong with the launch," the space agency said on Twitter, adding that it was "not clear what happened or at what point the vehicle failed."
NASA TV video showed the explosion of the Falcon 9 rocket about two minutes after it blasted off from Florida's Cape Canaveral at 7:21 a.m. PT.
The rocket "experienced a problem shortly before first stage shutdown," entrepreneur and SpaceX founder Elon Musk tweeted. "Will provide more info as soon as we review the data."
Falcon 9 was carrying a capsule loaded with cargo destined for the International Space Station, the Los Angeles Times reported. The Hawthorne-based SpaceX had hoped to land the 13-story rocket on an ocean barge after it separated from the capsule.
NASA officials planned to discuss the failed mission at a news conference Sunday morning.