The first of the climbers injured on Mount Everest have arrived in the capital, Kathmandu, as a video emerges showing the moment when an avalanche struck them.

Warning: this video contains repeated use of the 'F' word as the climbers deal with the shock of the avalanche.

Eighteen people died when a wall of snow smashed through the Everest Base Camp during Saturday's quake.

A sherpa among the injured, Gelu Sherpa, told reporters there is a lot of confusion on the mountain and the death toll will rise.

Climbers' photographs on social media show tents at the base camp flattened by rocks and snow.

Another 100 climbers higher up Everest at camps 1 and 2 are safe, including a group of New Zealanders travelling with the Wanaka-based guiding company Adventure Consultants.

It said it had lost five of its Nepali staff, but the climbers stranded at Camp 1 are safe and have plenty of supplies.

There were nearly 1,000 climbers and sherpas on Everest when the first avalanche struck, among an estimated 300,000 foreign tourists in the country for the trekking and climbing season.