ANCHORAGE, Alaska — Efforts to recover the three men who died in an avalanche Tuesday while they were on a guided heli-ski trip in the Chugach Mountains near Girdwood were halted because of dangerous conditions and difficult terrain — and may not resume until conditions improve, Alaska State Troopers said Friday.

The incident occurred around 3:30 p.m. Tuesday near the West Fork of Twentymile River, troopers said. The slide area is a mountain cirque about 9 miles northeast of Girdwood, in backcountry terrain accessible by air.

The three men caught in the avalanche were identified as 39-year-old David Linder, of Florida; 39-year-old Charles Eppard, of Bigfork, Montana; and 38-year-old Jeremy Leif, of Minnesota. Friends said the three met years ago in Minnesota and had been friends since high school.

They, and another person skiing with them that day, were clients of Chugach Powder Guides, a longtime Alaska heli-ski operator.

On Tuesday afternoon, a guide went out first and opened the run, laying down a line for the group to follow, according to an account from a friend of the four men. The surviving skier was second to transit the slope, then the three men were caught in the avalanche as they moved across. Chugach Powder Guides said the three men deployed air bags designed to help users stay near the surface of a moving avalanche.

The men were buried under at least 40 feet of snow at the bottom of steep terrain, authorities said.

On Thursday, avalanche experts, Alaska State Troopers and a mountain rescue expert assessed the slide area by air and on the ground, including the spot where signals from the men's avalanche beacons were last detected, troopers said.

"Due to a high risk of additional avalanches and the challenging location where the bodies of the three men are believed to be buried — the team has reached the consensus that recovery efforts are unfortunately not possible until conditions improve that allow for the safety of rescue teams who will need to spend significant time in the area," troopers said in an update Friday.

Troopers said that they and the heli-ski operator "will continue to evaluate conditions to determine when it is safe to allow rescue teams to operate in this area, recognizing that it may take some time for conditions to improve.

"We know that this is not the solution that the loved ones of these men were looking for today; however, it is the safest path forward for everyone involved," troopers said.

In recent days, forecasters with the Chugach National Forest Avalanche Information Center have cautioned backcountry recreators of the potential for triggering an avalanche on a weak layer of snow buried up to 2 feet deep in the snowpack across the region.

"Many human triggered avalanches have occurred on this weak layer in the past week, and conditions remain dangerous," the center said Friday.

The center also issued a special bulletin — in effect through Sunday morning — that warned of dangerous avalanche conditions in the mountains across a wide swath of Southcentral Alaska, noting recent snowfall on an unstable snowpack.