People sleep as they wait outside the departure terminal at the airport in Kathmandu, Nepal, April 27, 2015, following the April 25 earthquake.[Photo/Agencies]

Roads leading out of the mountain valley city of one million were jammed with people, many with babies in their arms, trying to climb onto buses or hitch a ride aboard cars and trucks.

Huge queues had formed at Kathmandu airport with people desperate to get a flight out.

Many said they had slept in the open since Saturday's quake, either because their homes were flattened or they were terrified that aftershocks would bring them crashing down.

High in the Himalayas, hundreds of climbers were staying put at the Mount Qomolangma base camp where a huge avalanche after the earthquake killed 17 people in the single worst disaster to hit the world's highest mountain.

Rescue teams, helped by clear weather, used helicopters to airlift scores of people stranded at higher altitudes, two at a time.