Jelle Veyt, a Belgian climber who fled the avalanche which struck just as he arrived at Camp 1, told BBC News: "There's not enough power in the helicopters sometimes to take a lot of people at once. So there's constantly helicopters flying back and forth from Camp 1 to Base Camp, taking two or three people.
"Once in a while they take jerry cans or gasoline. They refuel the helicopter and it goes back to Camp 1. This is constantly happening."
Alex Schneider and Sam Chappatte, a British couple who were caught in the avalanche, tweeted: "There is a mass exodus from camps 1&2, never seen so many choppers."
A team of 14 British Army Gurkhas attempting to become the first serving members of the famous Nepalese regiment to reach the summit of Everest were among those who were evacuated back to Base Camp yesterday, where they began work helping those who remain at the devastated site.
In the meantime footage emerged of the moment the avalanche struck, sending millions of tons of snow, ice and rock cascading down the mountain and engulfing the camp at 17,500ft where up to 42 separate teams were assembled to begin the first assaults of the 2015 climbing season on the summit.
The film, shot by a German mountaineer, Jost Kobusch, shows him remarking to a colleague "the ground is shaking" amid nervous laughter.
Moments later the vast rolling cloud of the avalanche appears and Mr Kobusch dives for a tent, telling his comrade "hold my jacket, hold my jacket" as they are engulfed. When the flow subsides, he emerges from his shelter looking for a more robust structure, saying: "Maybe in the kitchen tent ... Oh no, there is no kitchen tent."
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At least 17 at Base Camp, including Nepalese sherpas, perished in the immediate impact with another climber dying from his injuries. Sixty more were injured in the sprawling camp which hosts up to 1,000 people during the climbing season.
Apart from its human toll, the earthquake has also inflicted great economic damage on the tourism industry in Nepal.
The Everest climbing season was only just beginning after last year's season was unofficially cancelled following the deaths of 16 sherpas in another avalanche and a subsequent protest at what the guides said was the failure of the government to provide adequate insurance.
Hundreds of climbers pay an average of £30,000 ($59,781) each to make the pilgrimage to Everest every year, representing a significant chunk of the £1bn the Nepalese economy receives each year from tourism.
One tourism industry analyst said yesterday: "In the short term, Nepal is going to see its tourism fall to near-zero levels."
- The Independent