The owners of the unmanned commercial supply ship that exploded Tuesday over a launchpad in Virginia warned people to keep away from potentially hazardous debris and promised to figure out what destroyed the rocket that was supposed to ferry cargo to the International Space Station.

No injuries were reported following the first catastrophic launch in NASA's commercial spaceflight effort.

The accident at Orbital Sciences Corp.'s launch complex at Wallops Island was sure to draw criticism over the space agency's growing reliance on private U.S. companies in this post-shuttle era. NASA is paying billions of dollars to Orbital Sciences and the SpaceX company to make station deliveries, and it's counting on SpaceX and Boeing to start flying U.S. astronauts to the orbiting lab as early as 2017. This was the fourth flight by Orbital Sciences to the orbiting lab.

Orbital Sciences' executive vice president Frank Culbertson said things began to go wrong 10 to 12 seconds into the flight and it was all over in 20 seconds when what was left of the rocket came crashing down. He said he believes the range-safety staff sent a destruct signal before it hit the ground. The company said everyone at the site had been accounted for, and the damage appeared to be limited to the facilities. 

Bill Wrobel, director of NASA's Wallops Flight Facility, said crews were letting the fires burn out late Tuesday and set up a perimeter to contain them in the darkness

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There was no hint of any trouble until the rocket exploded. This was the second launch attempt for the mission. Monday evening's try was thwarted by a stray sailboat in the rocket's danger zone. The restrictions are in case of just such an accident that occurred Tuesday.

 Culbertson said the top priority will be repairing the launch pad "as quickly and safely as possible."

He said he could not guess how long it will take to determine the cause of the accident and to make repairs. Culbertson said the company carried insurance on the mission, which he valued at more than $200 million, not counting repair costs.

He stressed that it was too soon to know whether the Russian-built engines, modified for the Antares and extensively tested, were to blame.

"We will understand what happened — hopefully soon — and we'll get things back on track,"Culbertson told his team an hour after the failure. "We've all seen this happen in our business before, and we've all seen the teams recover from this, and we will do the same."

The Wallops facility is small compared to NASA's major centers like those in Florida, Texas and California, but vaulted into the public spotlight in September 2013 with a NASA moonshot and the first Cygnus launch to the space station.

Michelle Murphy, an innkeeper at the Garden and Sea Inn, New Church, Virginia, where launches are visible across a bay about 16 miles away, witnessed the explosion.

"It was scary. Everything rattled," she said. "There were two explosions. The first one we were ready for. The second one we weren't. It shook the inn, like an earthquake."

The roomful of engineers and technicians were ordered to maintain all computer data for the ensuing investigation. Culbertson advised his staff not to talk to news reporters and to refrain from speculating among themselves.

"Definitely do not talk outside of our family," said Culbertson, a former astronaut who once served on the space station.

This newest Cygnus cargo ship -- named for the swan constellation -- had held 5,000 pounds of space station experiments and equipment for NASA, as well as prepackaged meals and eagerly awaited crab cakes, freeze-dried for safe eating. It had been due to arrive at the orbiting lab Sunday.

By coincidence, the Russian Space Agency was proceeding with its own supply run on Wednesday, planned well before the U.S. mishap. And SpaceX is scheduled to launch another Dragon supply ship from Cape Canaveral in December; some items may be changed out to replace what was lost on the Cygnus.

NASA space station program manager Mike Suffredini told reporters that the station and its crew have plenty of supplies on board -- about five months' worth -- even without the upcoming launches.

Among the science instruments that were lost: a meteor tracker and 32 mini research satellites, along with numerous experiments compiled by schoolchildren. Suffredini promised the experimenters would get a chance to refly their work.

The two Americans, three Russians and one German on the orbiting lab were informed promptly of the accident.

Until Tuesday, all of the supply missions by the Virginia-based Orbital Sciences and California-based SpaceX had been near-flawless.

President Obama has long championed this commercial effort, urging that NASA focus its human spaceflight effort less on nearby orbit and more on destinations like asteroids and Mars. He was in Wisconsin for a campaign rally Tuesday evening and was kept abreast of the accident and its developments.

SpaceX's billionaire founder and chief officer Elon Musk — whose company is the face, in many ways, of the commercial effort — said he was sorry to learn about the failure. "Hope they recover soon," he said in a tweet.

Support poured in from elsewhere in the space community late Tuesday night.

"We are with you @OrbitalSciences and @NASA," former NASA astronaut Leland Melvin said via Twitter.

"Very sorry to see the Antares rocket launch failure," said Chris Hadfield, a former Canadian astronaut who served as space station commander last year. "Spaceflight is hard. Very glad that no one was hurt. Now time to sort out why & effects."

John Logdson, former space policy director at George Washington University, said it was unlikely to be a major setback to NASA's commercial space plans. But he noted it could derail Orbital Sciences for a while given the company has just one launch pad and the accident occurred right above it.

"It shows the wisdom of having more than one source" for launches, Logsdon said. Nevertheless, he added, "This is going to put the logistics chain for the station under some stress for a period of time."

U.S. Sen. Bill Nelson, a Florida Democrat who flew on a space shuttle right before the 1986 Challenger disaster, said in a statement, "Space flight is inherently risky. As we push the frontiers of space there will be setbacks. But our commercial space ventures will ultimately be successful."

The explosion also hit Orbital Science's stock, which fell more than 15 percent in after-hours trading.

The Associated Press contributed to this report.