A deadly avalanche in Khumbu Icefall on Mount Everest that claimed lives of Nepal's 16 Sherpa guides last week has triggered fear of the Icefall among climbers ahead of the climbing season.

Hundreds of climbers are gathering at Everest's 17,380ft Base Camp in early May, when the weather becomes more manageable, to attempt to scale the world's tallest mountain.

Why is Khumbu Icefall Deadly?

Khumbu Icefall, or the river of ice, is located at Khumbu glacier at about 18,000ft on the slopes of Everest. The Icefall has deep crevasses on its surface and fast-moving ice that makes the crevasses open or close in less than a day.

Fast-moving glaciers mean ice can break off any moment causing avalanches that threaten lives of climbers several thousand feet down as well.

Khumbu Icefall is considered the deadliest passageway to Everest's summit on the South Col route, which is the comparatively easier route up the mountain.

However, the fear and uncertainty because of Khumbu Icefall, which is the only way to reach the South Cole route, is always there.

"It's always something we fear," Sherpa mountaineering guide Adrian Ballinger, who will take climbers up the mountain through the Icefall in May, told the Associated Press.

Nima Sherpa, another guide from Himalayan ethnic community who is still mourning the loss of some of his colleagues and friends died last week said: "We look up at these chunks of ice blocks, pray and then try to get out of the area as fast as we can."

The Icefall has claimed lives of almost 30 climbers since 1963. Most were killed in avalanches, according to officials.

Sometimes climbers have to cancel their climb midway because of the dangers associated with the Icefall.

While climbers would make only two passes through the Icefall — once up to the summit and once down — Sherpa guides would go five to eight times, Ballinger said.

But he warned that the unpredictable Khumbu Icefall puts everyone at the same risk level.

"Every person has to make their own choice. If it wasn't the tallest mountain in the world, you would never put yourself on a glacier this active," he said.