Reports indicate that a serac fell onto the route, hitting the Sherpas. The full extent of their injuries isn’t immediately clear. According to the Himalayan Times, Ngima Sherpa’s injuries were the most severe and he had to be airlifted to Norvic International Hospital in Kathmandu. Dendi Sherpa is being treated at a clinic set up at Base Camp by the Himalayan Rescue Association. Kuntal Joisher, an Indian climber who is on the Satori team, said via Facebook that “Ngima's injury is more on the ribs and he’s in Kathmandu right now and doing good. And Tendi is in camp right now and resting and recovering for the next few days.”
Climbers making acclimatization trips to higher camps usually make their way through the Icefall in the early hours of the morning, before the sun heats up the ice and makes the area more erratic and unstable. After the serac collapsed, the damaged route was closed for two hours while a specialized team of Sherpas, known as the Icefall Doctors, climbed to the location with new ropes and ladders to make repairs.
The Icefall varies in width, from over half a mile to a third of a mile. As with many glaciers, the Khumbu moves as much as three feet a day in the center, while its edges remain still due to friction against rock walls. The top of the glacier moves faster than the bottom as well. It’s this dynamic of fast and slow moving sections that creates ice seracs that are over 30 feet high and crevasses, some of which are over 150 feet deep.
These towering pillars of ice can collapse without warning. When they do, ice particles, some the size of cars, explode across the route. In 2014, a collapsing serac killed 16 Sherpas who were waiting for a ladder to be replaced over a crevasse as they were ferrying loads to the higher camps. In 1970, six Sherpas were killed while supporting a Japanese expedition when a similar incident occurred.