A rocket operated by the aerospace company SpaceX has exploded on the launch pad at Cape Canaveral where it was being test-fired ahead of a launch.
The force of the blast shook buildings several miles away.
SpaceX said "an anomaly" had occurred while the rocket was being loaded with fuel. No-one was injured, it said.
The rocket's payload, an Israeli-built communications satellite for Facebook due to launch on Saturday, was also destroyed, it added.
Facebook, in partnership with Eutelsat Communications, had been due to use the Amos-6 satellite to deliver broadband internet coverage for swathes of sub-Saharan Africa as part of its Internet.org initiative.
