The death toll continues to mount following a deadly blizzard and avalanches in Nepal's Himalaya, but by Friday, hundreds of missing trekkers had been rescued.

At least 28 people have died in the blizzard and avalanches that struck Nepal on Tuesday, according to the Nepal Mountaineering Association. The Nepalese Tourism Ministry reports that 23 bodies had been recovered by Thursday.

In a statement promising continued rescue efforts, the ministry offered "deep condolences to the families and the relatives of the deceased who lost their lives in [these] unfortunate natural calamities."

The blizzard struck during normally mild October weather that draws thousands of tourists to Nepal for weeks-long hiking trips through the Himalaya.

Helicopter and walking teams had rescued some 219 tourist and Nepali trekkers on Thursday. Another 37 trekkers were reported rescued from Nepal's Thorung La pass on Friday.

The pass is the highest point at 17,765 feet (5,415 meters) in elevation on the Annapurna hiking circuit and seems to have been the site of the highest death toll, with more than a dozen dead, says Jiban Ghimire, a guide and outfitter based in Kathmandu.

At least 250 people had registered at a police checkpoint to hike through the area before the blizzard hit, Ghimire said.

Inexperienced Hikers, Real Mountaineering

The disaster on the Annapurna comes six months after an avalanche that killed 16 mountain workers, including 13 Sherpas, on Mount Everest, the world's tallest mountain at 29,035 feet (8,850 meters). The Everest workers were involved in helping high-paying customers through the rigors of scaling Everest, which typically draws experienced high-altitude climbers. (Read about how April's deadly Everest avalanche unfolded in National Geographic magazine.)

By contrast, the Annapurna circuit, roughly 200 miles (320 kilometers) west of Everest, is a much less demanding hike that attracts a range of tourists from around the world.

"Most trekkers on a route like the Annapurna circuit would have no mountaineering experience whatsoever. They'd be hikers, maybe without much wilderness experience," says Adrian Ballinger, owner and head guide of Alpenglow Expeditions, based in Squaw Valley, California.

During autumn, the 150-mile (241 kilometers) circuit usually sees mild weather, and snow is relatively rare, Ballinger said. "But in a storm condition, all of a sudden you're in extremely high altitude," he said. "It turns into real mountaineering."

View Images The body of a trekker killed by an avalanche in Thorung La pass is brought to the hospital in Kathmandu, Nepal, on October 17. Photograph by Narendra Shrestha, EPA

Caught Off Guard

The unexpectedly heavy snowstorm fell on the Annapurna range on Tuesday. At least three feet of snow fell on the mountains, stranding hikers dressed for fall weather, and as much as five feet fell at higher elevations.

"Unexpected snow brings unexpected avalanches," says Karl Birkeland of the U.S. Forest Service National Avalanche Center in Bozeman, Montana. "Any time you have heavy snowfall with wind-borne snow, you are increasing the odds of avalanches." (Related: "Avalanches Explained: How People Trigger Disasters.")

The most deadly individual avalanche on Tuesday seems to have been one that killed two Slovakian mountain climbers and three Nepali guides at the base camp beneath Mount Dhaulagiri, the seventh highest mountain in the world. The number of avalanches that occurred is unknown.

The blizzard followed heavy rains that battered Nepal and India earlier in the week, triggered by the remnants of Cyclone Hudhud, which itself killed at least eight people and displaced at least 300,000 more from coastal regions.

Nepal lacks an avalanche warning network, says snow scientist Jordy Hendrikx of Montana State University in Bozeman. "You need more than good weather forecasts; you need good measurements of the snow, and that is expensive," he says.

Weather reports are hard to come by while trekking in Nepal, but cell phones are widely used. Kathmandu-based development expert Keith Leslie noted in an email to National Geographic that "officials failed to warn tourists before they headed over the [Thorung La] pass when they knew a typhoon's tail was about to thrash the Himalaya."