Snow-covered trees are seen after an overnight storm in the Great Smoky Mountains National Park near Gatlinburg, Tenn., in October 2012.

GATLINBURG, Tenn. - Three Appalachian Trail hikers who were stranded in the snow without shelter have been flown to a hospital by helicopter.

According to Great Smoky Mountains National Park officials, Shawn Hood, Steven White and Jonathan Dobbins were taken to Mission Hospital in Asheville, N.C., on Friday afternoon.

The men, all from Gaffney, S.C., set out on Thursday for a 10-day backpacking trip. They used their cellphones to call for help Thursday night. Wind chills were 20 degrees below zero and snow drifts were up to 2 feet high.

Rescue efforts were hampered by weather, road and trail conditions and the remote location.

Rangers eventually reached the men with warm clothing and tents. They were being treated for hypothermia and possible frostbite. All three were very weak and could not walk.