A rocket carrying a commercial unmanned spacecraft loaded with supplies for the International Space Station exploded just seconds after launch on Tuesday.

The first stage of Orbital Science's two-stage Antares rocket burst into flames as it rose from its launch pad at NASA's Wallops Flight Facility in Virginia at 6:22 p.m. ET. The company's Cygnus capsule and more than 5,000 pounds (2,200 kilograms) of cargo were destroyed, but NASA said no one was injured.

The cause of the accident was not immediately known. It came after a flawless countdown during which Orbital's team "was not tracking any issues," NASA said in a status update.

"It is far too early to know the details of what happened," Frank Culbertson, Orbital's executive vice president, said in a statement. "As we begin to gather information, our primary concern lies with the ongoing safety and security of those involved in our response and recovery operations."

The rocket rose just a short distance from its launch platform before it started breaking apart.

Let our news meet your inbox. The news and stories that matters, delivered weekday mornings. This site is protected by recaptcha

"Parts were sent flying everywhere, and then the vehicle fell back to the pad, exploding in an even larger fireball, setting the entire area on fire," CollectSpace.com editor Robert Pearlman, who witnessed the launch, told Space.com.

This would have been Orbital Sciences' third official cargo mission to the space station for NASA under the terms of a $1.9 billion contract that calls for a total of eight delivery missions. Orbital's Cygnus capsule was filled with food, water, experiments and other gear for the astronauts aboard the space station.

During a post-accident news conference, Culbertson said the rocket, the capsule and the cargo were valued at about $200 million, but that figure doesn't include the damage done to the Wallops launch pad and its surroundings. He said Orbital had launch insurance to cover its losses.

Culbertson urged those near the launch site to be careful if they find debris: "This is an accident site, and this was a rocket. If you find anything in the shore area or that came down on your farm or in your yard, alert the local authorities, definitely do not touch it and keep people away from it."

Anyone finding debris should call NASA's hotline for this purpose — the number is 757-824-1295.

The space station's crew won't go hungry: NASA officials said nothing urgently needed was lost, and the Russian Space Agency is scheduled to send up cargo in a separate Soyuz launch from the Baikonur Cosmodrome in Kazakhstan on Wednesday. Even if no more cargo spaceships were sent up, the station has enough supplies to last until next March, said Michael Suffredini, NASA's space station program manager.

Another company, California-based SpaceX, has a separate $1.6 billion contract to resupply the space station using its commercial Falcon 9 rockets and Dragon capsules, launched from Cape Canaveral Air Force Station in Florida. A SpaceX Dragon returned to Earth over the weekend at the end of one mission, and another SpaceX mission is scheduled for launch in December.

Tuesday's launch failure is not expected to have an major impact on SpaceX's operations. In a Twitter update, SpaceX founder Elon Musk said he was sorry to hear about Orbital's setback. "Hope they recover soon," he wrote.

The Orbital launch was originally scheduled for Monday, but it was postponed a day because a sailboat wandered into a restricted area downrange of the launch pad just before the scheduled liftoff.

A NASA launch commentator said the Cygnus' cargo included some "classified crypto equipment" that the ground crews were told to prioritize. The equipment was likely to have been used for secure space-to-ground communications. The capsule held 32 Cubesat nanosatellites that were to have been deployed from the space station.

An accident investigation team was formed by Orbital with assistance from NASA and the Federal Aviation Administration. White House deputy press secretary Eric Schultz said President Barack Obama was briefed on the launch failure and was continuing to get updates.

In the past, Orbital has had to deal with issues involving the Antares rocket's kerosene-fueled AJ-26 engines, which are based on Soviet-era Russian hardware. In 2011, a test-stand fire ruined one of the engines and led to a full-scale inventory check. Another engine failed during a test this May, and some reports characterized the failure as an explosion. However, it will probably take months to determine whether the engines or other components were at fault in Tuesday's launch failure.