It takes a lot to rattle Swiss climber Ueli Steck. The 36-year-old holds solo speed records in the Alps and has several groundbreaking first ascents to his name. But on April 27, while attempting to climb Mount Everest, it wasn't the mountain that nearly killed him but a mob of angry, stone-wielding Sherpas, who descended on Steck and his two climbing partners as they hid in their tent. "All I could hear was them shouting, 'Give us the guy – we will kill him first and then the other two,'" he told a Swiss website.

Steck, Simone Moro, 45, of Italy, and Jon Griffith, 29, of the U.K., had gotten into an argument with the Sherpas earlier in the day while climbing above Camp 2 on the sheer Lhotse face. The Europeans were climbing independently and Alpine-style – fast, light, and unroped – while, 150 yards away, roughly 15 Sherpas were attaching ropes to the face to be used by the commercial guiding companies. There are no regulations that prohibit a faster climbing team from passing a slower one, but the commercial outfitters generally consider the route to be off-limits for however long it takes to get the fixed lines in place. The number of clients paying upward of $70,000 to join these commercial expeditions has surged in recent years and accounts for more than half of the roughly 4,000 climbers on Everest every year. These fixed ropes represent the lifeline to the top for them, and bottlenecks have become one of the biggest dangers on the mountain.

Steck and his crew eventually had to step over the Sherpas' ropes to reach their tent, at which point the lead Sherpa started shouting and hitting the ice with his axe. "Motherfucker!" Moro exclaimed in broken Nepali. "What are you doing?" The Sherpas claimed ice had been dislodged onto them. Griffith thinks it was all about pride. "We believe that we hurt his honor by climbing so fast," he says. The angry Sherpas abandoned their efforts and descended back to Camp 2.

It was a collision of both culture and climbing philosophies: Independent climbers like Steck feel that Everest – just like every mountain – should be open to all, anytime. The commercial outfitters, on the other hand, prefer a structure that favors their slow-moving – and often less experienced – parties. The Sherpas are largely employed by the outfitters and, as overcrowding has become prevalent on Everest, things came to a boil.

The tension among Westerners and Sherpas has a precedent – climber Steve House says his team was confronted last year, after descending another Himalayan peak, Makalu, using fixed lines set by Sherpas from a different expedition; and speed-climber Chad Kellogg had a run-in the day before Steck did, in the same place. However, Sherpas had never banded together in such a threatening way. Westerners and Nepalese agree that

Sherpas' working conditions need improvement – but the way in which things escalated this time have many worried about a new and ominous threat. "This is really bad," says Conrad Anker, an Everest veteran. "There wasn't much dignity on either side."

Back in camp 2, the commercial guides listened to things unfold over the open radio frequency, agonizing that a day of rope fixing had been wasted. It's common for the guiding companies to pool their Sherpas for rope-fixing efforts that benefit everyone climbing the mountain – everyone who has either paid or been paid to climb, that is.

The guides asked Moro to descend immediately to try to mend fences with the Sherpas. In broken Nepalese, he replied that he would speak to "the fucking Sherpas" as soon as he got back. Moro's casual use of profanity in his non-native language rubbed both the Sherpas and the Western guides the wrong way at the time. "Simone is a funny guy," says Sumit Joshi, a Nepali guide who was in Camp 2 at the time of the incident. "But he's always cutting jokes and swearing, and that wasn't well received." Steck, meanwhile, continued higher on the face to finish the job that the Sherpas had started, to help appease the situation.

Soon after the three Western climbers arrived back in Camp 2, American guide Melissa Arnot, who holds the record for most Everest ascents by a female, came running toward them. "Melissa said, 'There's a mob coming for you – run,' " Griffith recounted from his home in Chamonix, France. Some of the Sherpas armed themselves with rocks while Steck, Griffith, and Moro tried to back away. It was too late – the rope-fixing team had rallied a dozens-strong mob.

Kiwi guide Marty Schmidt confronted one Sherpa who had picked up a rock, reportedly knocking it from his hands, shouting, "No violence!" Schmidt was then punched. Steck was punched in the face by the lead Sherpa from the rope-fixing team, and then struck by a rock. "There's no point in fighting back against 100 people," Steck says from his home in Switzerland. "All you can do is take the beating."

As Steck and Moro received punches and kicks to the face and ribs, Griffith felt it was spiraling out of control, and thought, "This is it – they were collecting us one by one to stone us." Finally, Melissa Arnot, Greg Vernovage, a guide from longtime Everest outfitter International Mountain Guides, and Sherpa Pang Nuru pulled Steck back inside the tent. "I think the only reason they didn't kill him is because Melissa's a woman," says Griffith.

Eventually, the Sherpas agreed that if Moro would apologize, on his knees, they would leave, and that if the Europeans left the mountain immediately, they would be spared further harm. With split lips and severely bruised ribs, Steck, Moro, and Griffith packed up and began descending a totally unprotected route through a field of crevasses, down to Base Camp. "We hurried to the first crevasse ladder and if anyone started chasing us we would cut every line and ladder on the way back to Base Camp," Griffith says. "I've never been so scared in my life."

A week later, Steck and Griffith were back home and Moro was operating his volunteer helicopter-rescue operation in Nepal. But even with the climbers gone from the mountain, the Westerner-Sherpa relationship was in tatters. Arnot, who many credit with saving Steck's life, wrote on her blog that "Something shifted the balance."Everest Base camp is a village in itself. There are mess tents with pool tables and full internet connectivity; people spend downtime playing horseshoes or updating blogs. Nonetheless, it is incredibly remote – a three-day hike from the nearest Nepalese village police station – and relies on its own set of rules and social norms.

With the guiding trade booming, Sherpas are making more money than ever in one of the poorest countries in the world (the average annual income is $300; Sherpas make up to $5,000 in one season). But they're faced with the lion's share of the danger since they are constantly shuttling heavy loads back and forth, and they still receive a fraction of the money made by the outfitters.

Nepali guide Sumit Joshi believes the threat was more perceived than real and even somewhat justified. "They were throwing rocks onto the tent, but not at people," he says. "The fixing team was venting the frustration of all highly skilled Sherpas, who want more respect from their Western colleagues. We often hear our Western outfitter friends acknowledge that the Sherpa climbers deserve more," Joshi continues. "But what are they actually willing to give?"

"If the Sherpas had been as media savvy as the Euros, the story hitting the news would have been 'Euro climbers insult, threaten, and endanger Sherpas,' instead of 'Sherpas attack climbers,' " says IMG co-owner Eric Simonson. But according to Cory Richards, a National Geographic photographer and professional climber, if anybody needs to take ownership of the situation, it's the commercial-guiding industry itself. "They are the ones responsible for the work conditions," he says.

The greatest loss in the wake of this incident could be Everest itself as a mountain for true adventure. It's being reported that the commercial operators will formally ask permission from the government to close sections of the mountain for their Sherpa teams next year. "If they say the mountain is closed until the ropes are fixed, then this really is the death knell for adventure on Everest," says Mark Richey, former president of the American Alpine Club. Some Western outfitters are even pushing for every climbing permit to be printed with new rules stating no one is to climb during rope fixing. The plan heavily favors commercial expeditions­ – but for Nepal's Ministry of Tourism, Everest represents big dollars. Conrad Anker says the government is part of the problem. "They're receiving millions of dollars a year from climbing permits," he says. "Hardly any of it makes it back to the Sherpa communities."

"You can't say that part of the mountain is off-limits," says Cory Richards. "Last year I wanted to take photos of the rope fixing and was told by some Western guides that I wasn't allowed to be up there. Since when does that infrastructure take precedence over real climbing? Something's been lost."

Two days after the attack, Steck, Moro, and Griffith came face-to-face with the Sherpas who attacked them, after a "peace treaty" was drawn up and signed by dozens of Western guides and Sherpas. Despite the symbolism, Steck thinks the worst may be yet to come. "I think this 'ceremony' calmed the situation down, but it certainly did not solve the problem," he said. He remains haunted by what happened. "This 'peace deal' was just a pretext for everyone to get out of the situation. . . I am so disappointed, and my trust is gone. I could not go back to this mountain. Who can assure me that an angry mob is not cutting my rope or burning my tent?"