An F-22a Raptor crashed Wednesday morning about 35 miles (56kms) northeast of the Edwards Air Force Base in California.
The United States Air Force said in a statement that it was trying to determine what caused the crash of the jet, and that the status of the pilot is currently unknown.
This is the second time the $142 million a pop stealth fighter has crashed; the last accident occurred during a test flight in December 2004.
The Lockheed Martin/Boeing F-22 Raptor entered service in 2005, and is regarded by experts as being the best aircraft ever deployed by the United States. The US Government values the plane so much that unlike other aircraft, the Raptor is not available for export to US allies.