Two Marine MV-22 Osprey tilt-rotor aircraft and two Marine UH-1Y Huey helicopters flew for a combined total of 21 hours Wednesday over Nepal's rugged terrain in the thus-far unsuccessful search for a Marine Huey with six Marines and two Nepalese  on board that went missing Tuesday.

The search and rescue operation was suspended at nightfall and would be resumed at dawn Thursday, said Col. Steve Warren, a Pentagon spokesman.

Warren said the military was aware of other reports that the Huey had been sighted. However, the Pentagon and U.S. Pacific Command rejected those reports.

"We don't have anything independently to confirm those reports," Warren said.

Warren said the military was aware of reported transmissions from the missing Huey that the helicopter was running low on fuel shortly before the Huey went missing without reporting an emergency or giving a location.

"At this time, the status of those manifested on the flight is unknown," said a statement from the military's Joint Task Force 505, which is leading U.S. relief efforts in Nepal following two major earthquakes.

Lt. Gen. John Wissler, commander of the 3rd Marine Expeditionary Force, has been designated by Adm. Samuel J. Locklear, commander of the U.S. Pacific Command, as commander of Joint Task Force 505.

The missing helicopter was assigned to Marine Light Attack Helicopter Squadron 469 based at Camp Pendleton, Calif.

The military's aid response, coordinated with the U.S. Agency for International Development, began after a 7.8 magnitude earthquake struck Nepal on April 25. A second earthquake with a 7.3 magnitude struck Tuesday.

-- Richard Sisk can be reached at richard.sisk@military.com