At Least 63 Americans Missing In Nepal-Tibet Floods

Among those caught in the disaster were travelers associated with the India-based Isha Foundation, which told ABC News that 22 Americans were among a 77-person tour group at an immigration center near the Nepal-Tibet border when the flooding struck.

Three additional missing Americans were reportedly traveling with the Nepalese company Fishtail Tours and Travel, which confirmed that the U.S. nationals were among tourists still unaccounted for.

The disaster reportedly began roughly 12 miles northeast of the Rasuwagadhi border crossing, where an enormous glacial collapse sent ice, rock, and debris plunging into the valley before a devastating surge traveled downstream toward populated areas.

Entire stretches of critical infrastructure have been devastated, complicating an already dangerous rescue mission as emergency crews navigate unstable terrain, thick mud, high water, and areas accessible primarily by helicopter.