A SpaceX rocket carrying a resupply spacecraft bound for the International Space Station exploded less than two minutes after launch earlier today.
The spacecraft was unmanned and no one was injured in the accident.
SpaceX, which has already flown six official resupply missions for NASA, is slated to begin carrying astronauts to the space station in 2017.
"We are disappointed in the loss of the latest SpaceX cargo resupply mission to the International Space Station," NASA Administrator Charles Bolden said in a statement Sunday. "However, the astronauts are safe aboard the station and have sufficient supplies for the next several months. We will work closely with SpaceX to understand what happened, fix the problem and return to flight."
The rocket lifted off from Cape Canaveral Air Force Station in Florida.
SpaceX tweeted that the rocket "experienced an anomaly on ascent" and that it is investigating the explosion.
Elon Musk, CEO and CTO of SpaceX, also tweeted, at first writing, "Falcon 9 experienced a problem shortly before first stage shut down. Will provide more info as soon as we review the data." He offered more detail in a later tweet: "There was an overpressure event in the upper stage liquid oxygen tank. Data suggests counterintuitive cause."
In September 2014, NASA announced that it was contracting with SpaceX and Boeing Co. to begin carrying astronauts back and forth from the space station beginning in 2017. The signing of the Commercial Crew Transportation Contracts meant that NASA was moving to, once again, begin launching astronauts from American soil.
The U.S. has been relying on the Russians to ferry its astronauts to the space station since retiring its fleet of space shuttles in 2011.
The SpaceX cargo craft that exploded was carrying more than 4,000 pounds of supplies and equipment, including what NASA called "critical materials" for onboard science and research investigations, like tracking meteors entering Earth's atmosphere, growing food in space and tackling in-space crew health risks.
The SpaceX spacecraft also was carrying two pairs of HoloLens, Microsoft Corp.'s virtual reality headsets.
Sunday's accident comes after NASA's other commercial space flight partner, Orbital Sciences Corp., saw its Cygnus cargo craft and the Antares rocket it was riding explode just after launch last October. Also unmanned, the Cygnus cargo craft was carrying about 5,000 pounds of scientific experiments and supplies for the orbiting space station.
And in April, a Russian spacecraft carrying food, scientific supplies and oxygen to the space station, had trouble soon after launch and plunged back to Earth.
NASA noted on its Web site that another resupply craft is set to launch on July 3.
"SpaceX has demonstrated extraordinary capabilities in its first six cargo resupply missions to the station, and we know they can replicate that success," wrote Bolden. "We will work with and support SpaceX.... This is a reminder that spaceflight is an incredible challenge, but we learn from each success and each setback."
Astronaut Scott Kelly, who is working on the space station now, was quick to comment on the accident, which he watched from the orbiter. "Today was a reminder spaceflight is hard," he tweeted on Sunday. "Tomorrow is a new day. Good night from @space_station. #YearinSpace"