A powerful earthquake in Nepal on Saturday triggered an avalanche on Mount Everest, climbers said, raising fears for those on the world's highest peak a year after another avalanche caused the deadliest incident on the mountain.
An official from the Nepal tourist board confirmed that part of Everest base camp had been buried, and that ten people had been killed.
"The toll could go up, it may include foreigners as well as sherpas," said Gyanendra Shrestha.
Tiku Gurung, an executive committee member of the Expedition Operators Association, which represents Everest's Sherpas, said there were reports that five climbers had died. It was not clear whether this was in addition to the eight killed at base camp, or an alternative toll.
"We're not exactly sure but we believe five are dead," he said. "There are so many people injured but we do not know the exact number. The avalanch came from so many sides", he told the Telegraph.
He said there were currently between 700 and 800 climbers on the mountain.
Romanian climber Alex Gavan said on Twitter that there had been a "huge avalanche" and "many, many" people were up on the mountain.
The advance base camp for people climbing Mount Everest sits on the mountain's north slope at about 21,000 feet (AP)
"Running for life from my tent," said Mr Gavan. "Everest base camp huge earthquake then huge avalanche."
Another climber, Daniel Mazur, said Everest base camp had been "severely damaged" and his team was trapped.
"Please pray for everyone," he said on his Twitter page.
Adrian Ballinger, a mountain guide who has climbed Everest six times, tweeted:
An earthquake measuring 7.9 magnitude struck west of Kathmandu causing buildings to collapse, killing at least 108 people, injuring more and leaving a pall of dust over the city.
An avalanche in April 2014 just above the base camp on Mount Everest killed 16 Nepali guides. April is one of the most popular times to climb Everest before rain and clouds cloak the mountain at the end of next month.