10 missing after avalanche on Mount Everest

(CNN) -- Up to 10 people were missing Friday after a high-altitude avalanche on Mt. Everest, a climbing company executive told CNN.

Edmund Hillary and Tenzing Norgay smile after descending from Mount Everest in 1953. The pair were the first climbers to summit the world's tallest mountain.Locals celebrate first Everest ascent

Gordon Janow with Alpine Ascents International in Seattle said the avalanche took place just above base camp in the Khumbu Ice Fall.

Climbing season on the world's highest peak begins no earlier than May 15.

Climbers and guides had been setting the ropes for the route, acclimating to the climate, and preparing the camps along the route, said Janow.