The company acknowledged it had been conducting “a series of engine tests on a Crew Dragon test vehicle” in Cape Canaveral in Florida this weekend.
“The initial tests completed successfully but the final test resulted in an anomaly on the test stand,” said a statement.
Images apparently showing the spacecraft bursting into flames appeared on social media but SpaceX and NASA have so far not commented on them.
NASA administrator Jim Bridenstine said that the space agency had been notified about Saturday’s anomaly.
“This is why we test,” he said. “We will learn, make the necessary adjustments and safely move forward with our Commercial Crew Program.”
Led and founded by billionaire Elon Musk, SpaceX has developed multiple launch vehicles and rockets as part of its plans to reshape the space industry – primarily by reusing and recycling its Falcon 9 launch rockets.
The company’s technology has to be rigorously tested before it can be used to launch or carry people into space.
Last month, an unmanned SpaceX Dragon capsule splashed down in the Atlantic after a short stay at the International Space Station.
It was the first time a commercial space system built for humans had been successfully flight tested by NASA.
The capsule – containing a dummy called Ripley – reached hypersonic speeds after detaching from the ISS and splashed down off Florida.
It was being tested as part of NASA’s commercial crew programme which aims to see the agency collaborate with private industry to support America’s space agenda.