Against a breathtaking backdrop on Mt. Everest at 24,000 feet, three mountaineers were reportedly attacked by scores of people this week—a violent assault that included being kicked in the gut, punched in the face, threatened with knives, and pelted with rocks. Scuffles occasionally break out on the world’s highest peak, but such violence is rare. More surprising, however, were the identities of the assailants. The large vigilante squad turned out to consist largely of Tibetan Buddhist Sherpas.

The story of high-altitude workers banding together to attack three men who apparently offended them defies expectations. In the popular narrative, Sherpas revere the mountain goddess and live in a parallel universe, untouched by the greed and egoism that drives their western clients. Ignored, even exploited, the Sherpas seldom get frustrated or angry about their working conditions because negative emotions pollute the mountain’s sacred space. Moreover, taking the life of a sentient being is repugnant, a sin that prevents many devout Buddhists from slaughtering animals.

But on Saturday morning, Simone Moro, a sentient being himself, feared he was about to become an exception. Renowned for pioneering winter ascents in the Karakorum and Himalaya, the Italian alpinist was part of a three-person team attempting a new route. They were climbing without Sherpas, bottled oxygen, fixed lines or other aids.

Along the way, a team of Sherpas was fixing rope up the slope. According to Moro’s account, these Sherpas asked them to wait until the job was done. But Moro and his teammates told them they didn’t need the fixed rope and were taking a different route up. The westerners climbed 150 feet to the side of the ropes, then, upon reaching their camp, stepped over the fixed lines to reach their tents.

Or tried to. At that point, a Sherpa above them began “shouting and banging the ice with his axe erratically,” according to a statement from Moro and his teammates. The Sherpa then slid down the rope and crashed into Moro’s teammate, Ueli Steck of Switzerland. The Sherpa accused the westerner of knocking off ice to hit the Sherpa below.

In Moro’s statement, he said he cursed at them, and Moro’s teammate told The Guardian that he called the Sherpa a “motherfucker.”

The Sherpa allegedly then swung an ice axe at the men, and the shouting match ended with the Sherpa ordering his 17-person team to stop fixing rope and return to a lower camp. To diffuse the situation, Moro’s team finished the work for the Sherpa, fixing nearly 900 feet of fixed lines, but that only angered the Sherpas further.

The incident seemed to be over, and Moro and his teammates resumed the climb, later returning to the lower camp.

But, according to Moro, some 100 Sherpas, their faces covered in scarves, were ready for the men. The mob stormed their tents, punched and kicked the climbers, hurled rocks and pulled out knives. “The climbers were told that by night one of them would be dead and the other two they would see to later,” the statement from Moro said.

The rioting lasted about an hour. Climbers on other teams stepped in to shield Moro and his colleagues, who, spitting blood, packed up their essential gear and fled, taking a dangerous, highly crevassed back route down the mountain. Melissa Arnot, one of Moro’s defenders, described blocking him “from unexplainable violence and anger.”

The riot confounded the western mountaineers. “Something shifted the balance for a moment,” wrote Arnot in a statement. “My only hope is that it shifts back quickly, and everyone can resume their jobs.”

Moro wondered at “the final straw that broke” Sherpa-Western relations. The working conditions on the mountain were especially harsh that morning as the Sherpa fixed rope in biting winds and freezing temperatures. Had Moro’s expletive sparked a labor riot?

The economic differential between the men throwing rocks and the men being hit by them is enormous. Sherpas earn $3,000 for 3 months of hard labor on the slopes of Everest. That’s a high salary by Nepali standards, but an experienced western mountaineer—through guiding and sponsorship—can earn up to 100 times as much. Although Moro eschewed rocks and knives, he wasn’t unarmed. As a mountaineering celebrity, Moro is a public relations powerhouse with first ascents, charity projects, and heroic rescues to his credit— and a publicist to promote it all. Even now, as millions sympathize with his ordeal, we barely know the names of the men who assaulted him, or why they did it.

Police have reportedly interviewed them, but western journalists have found them hard to reach. Despite our phone calls and emails, Nepal's Ministry of Tourism has not released their contact information. It will be some time before a full account of this incident emerges.

Labor relations on Everest have been building to a flashpoint for a century. At first, the Sherpas controlled a near-monopoly on high altitude work for western expeditions. They had effectively unionized by the 1920s, demanding preferential treatment and fair wage, staging strikes if forced to work alongside other ethnicities. Leveraging their reputation as the most experienced indigenous mountaineers, Sherpas gradually became one of the wealthiest and most powerful ethnic groups in Nepal.

At the same time, individuals born into other ethnic groups began to pose as Sherpas to secure jobs. Tenzing Norgay, the man who made the Sherpas famous, actually was born into a rival Bhote ethnic group and only identified as Sherpa after he and Edmund Hillary became the first to summit Everest. It wasn’t until after Everest, once Tenzing had achieved celebrity, that the Sherpa community accepted him. Even today, western mountaineers are often oblivious to the cultural and linguistic diversity among the “Sherpas” they’ve hired and the seething resentment of business and ethnic rivals on the mountain.

Moro, who occasionally guides private clients on Everest and doesn’t hire a Sherpa workforce, had become a rival, too.

And as he learned on Saturday, sometimes these tensions and inequities can have violent consequences.

Peter Zuckerman and Amanda Padoan are authors of Buried in the Sky: The Extraordinary Story of the Sherpa Climbers on K2’s Deadliest Day, which won the National Outdoor Book Award and the Banff Mountain Book Award.