Two Arizona men who set out last week to float the San Juan River in southeastern Utah were plucked by helicopter from a canyon Monday after their raft was immobilized by ice, authorities said.

The San Juan County sheriff's office said Tom Miller, 46, and Dave Stilley, 31, both of Flagstaff, apparently suffered no ill effects from their ordeal, which began Thursday and ended with their rescue by a Colorado Army National Guard helicopter about 5:55 p.m. Monday.The two were reported missing after failing to contact relatives Sunday, and a search was launched the following day.

Deputy sheriffs and the National Park Service said the pair had intended to float from Mexican Hat toward Lake Powell, ending at the Clay Hills area near Halls Crossing, but weather conditions worsened after they embarked and the river became impassable.

Stilley's brother, Tom, said he chartered a private plane out of Page, Ariz., to search for the boaters. He and the pilot were making one last sweep up the river from Gooseneck State Park Monday afternoon when they saw two men in a steep canyon signaling with a mirror.

The Army helicopter happened to be flying through the area en route to a training mission at Nellis Air Force Base, Nev., and its crew agreed to handle the rescue.