The family stopped to take a break on the West Fork of the Duchesne River. The four children walked about 50 feet away to the edge of a ridge to look down at a creek, when the snow gave way under their feet, causing three of them to slide down an embankment, according to a press release from the sheriff's office.
Coleman and Traven were buried in about 3 feet of snow; the third child was not buried.
Their parents worked to find them, but blocks of heavy snow made it difficult, the news release said. The father Jason kept digging while the mother Janette left the area to call 911.
The boys were found by their father after about 30 minutes, and the parents began CPR, while "the two girls, as full of courage as their parents, climbed the mountain and waved in AirMed helicopters and search and rescue teams," the sheriff's office wrote in a press release.
The boys were transported to Primary Children's Medical Center, where they were pronounced dead.
Gordon inspected the slide area on Saturday as part of his regular rounds in the backcounty of the western Uintas and said the slab of snow the boys were caught in was about 150 feet wide and 2 or 3 feet deep, but only moved about 50 vertical feet
Most observers would not likely had thought it posed a serious risk of slide. The area is part of a large basin and the slope where the slide occurred was not particularly steep, he said.
"This isn't like some really crazy slope that you'd be looking at and think, 'of course, what were those people thinking?' " Gordon said. "It's just at little hill that had enough weak underlying snow with a strong slab on top."
Anyone who wants to help the Sweats can donate to the Memorial Funds of Coleman and Trevan Sweat at Wells Fargo Bank and Utah Community Credit Union.
"Our collective thoughts, prayers, and energy go out to friends and family of the young boys," the center posted on its website. The center also thanked the heroic efforts of all those involved, particularly both the Wasatch and Summit County search and rescue teams.
The Sweat family could not be reached for comment and has asked for privacy.