The company said in a statement that all personnel have been accounted for.
The rocket explosion, a contender for the largest in American history, marks a significant setback for Jeff Bezos and NASA.
Footage of the incident shows the rocket erupting into a massive fireball, sending towering flames and thick smoke into the night sky.
Jeff Bezos described the incident as a "very rough day" in a major setback for the company's space venture. Elon Musk said of the incident: "Rockets are hard." ...
The spacecraft had been undergoing a static hot-fire test.