Saturday's 7.9-magnitude quake was the strongest to hit Nepal for 81 years. It also shook neighbouring India, China and Bangladesh. Early on Sunday, the official death toll stood at more than 1,300 people in Nepal.
Romanian climber Alex Gavan made a desperate appeal for a helicopter to fly in and evacuate climbers: "Many dead. Much more badly injured. More to die if not heli asap."
Carsten Lillelund Pedersen, a Danish climber, said about 40 people were being treated in a makeshift hospital at a tent at base camp. He said many of those injured had back injuries from being hit by rocks and ice when running from the avalanche.
The poor visibility after the first avalanche meant it was "difficult to see the following avalanches, and there are so many - maybe one every 5 min. - that I have stopped counting", Pedersen said on Facebook.
Mohan Krishna Sapkota, joint secretary in the Nepalese tourism ministry, said the government was struggling to assess the damage on Mount Qomolangma because of poor phone coverage.
"The trekkers are scattered all around the base camp and some had even trekked further up," Sapkota said. "It is almost impossible to get in touch with anyone."
Choti Sherpa, who works at the Mount Qomolangma Summiteers Association, said she had been unable to call her family and colleagues on the mountain. "Everyone is trying to contact each other, but we can't," she said. "We are all very worried."
Last year's tragedy prompted the Sherpa guides to complain that their safety was being neglected, but there were no immediate recriminations on Saturday.
"This will definitely have some impact on climbing activity, but this is a natural disaster. No one can do anything," said Ang Tshering Sherpa, president of the Nepal Mountaineering Association.
At the Annapurna mountain range, where scores were killed in the nation's worst trekking accident last year, many hikers were stranded after the earthquake, according to messages on social media, but no fatalities had been reported.
Stan Adhikari, who runs the Mountain House lodge in Pokhara near the mountain range, said the city had escaped the worst of the damage. "There hasn't been much damage," Adhikari said.
He said there were about two dozen guests at his lodge, including people from Europe, the United States and China. The road from Pokhara to Kathmandu was not passable but he hoped it would open on Sunday.