But reports later said that some remains had been found in the aircraft and would be sent for DNA analysis.
Fifty people and five dog teams would carry out an extensive search of the site for Mr Fossett's remains, he added.
On Thursday British entrepreneur Richard Branson paid tribute to his friend and fellow adventurer.
"The most important thing is that the family know what's happened," he said. "He led an extraordinary, absolutely remarkable life, and now we can remember him for what he was and move on."
The National Transportation Safety Board will be responsible for examining the wreckage.
But a local official said snow was expected over the weekend, potentially hampering the investigation.
The wreckage was located two days after identity documents bearing Mr Fossett's name - including a pilot's licence - as well as cash and a sweatshirt were found by hiker Preston Morrow.
Mr Morrow had been returning from a mountain walk when he spotted the items in dirt and pine needles west of Mammoth Lakes.
An employee at a sporting goods store, Mr Morrow said he handed them over to police after unsuccessful attempts to contact the Fossett family.
The BBC's Rajesh Mirchandani, in Los Angeles, says the items were found outside the vast area searched after Mr Fossett went missing - and also in a different direction to that in which he was thought to have flown.
Mr Fossett took off from the ranch of hotel magnate Barron Hilton, south of Yerington, Nevada, on 3 September 2007 on a flight that was expected to last three hours.
In 2002, he became the first person to circle the globe solo in a balloon and had about 100 other world records to his name.
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