A strong earthquake aftershock struck India and Nepal on Sunday, shaking buildings in New Delhi and triggering an avalanche in the Himalayas.
The United States Geological Survey said the tremor was 6.7 magnitude, less than the 7.9 quake that struck the region on Saturday. The Sunday aftershock registered at a shallow depth of 10 kilometers (6 miles), making damage very likely within a radius of 50 kilometers (31 miles).
A Nepal police official says at least 2,200 people have been killed in the initial earthquake and aftershock Saturday, including at least 700 in Kathmandu.
"Another one, we have an aftershock right now, oh shit," Indian mountaineer Arjun Vajpai told Reuters by telephone from advanced base camp on Mount Makalu, 20 km (12 miles) from Everest. "Avalanche!" he shouted. Screams and the roar of crashing snow could be heard over the line as he spoke.
At Everest base camp, Romanian climber Alex Gavan tweeted that the aftershock had set off three avalanches.
"Horrible here in Camp 1 - avalanches on 3 sides," tweeted climber Daniel Mazur from an advance base on Everest.
The aftershock hit Nepal and the eastern part of the north Indian state of Bihar.
"There is no way one can forecast the intensity of aftershocks so people need to be alert for the next few days," said L.S. Rathore, chief of India's state-run weather office.
Everest rescue efforts
Hundreds of climbers, many foreigners, remained stranded on the mountain as Sunday's aftershock hit.
In Everest's worst disaster on Saturday, the bodies of 17 climbers were recovered from the mountain after being caught in avalanches. A plane carrying the first 15 of 61 injured climbers landed at Kathmandu airport on Sunday around noon local time.
There was nearly 1,000 climbers and sherpas on Everest when the avalanche struck, claiming the highest toll of any disaster on the world's highest mountain.
Climber photographs on social media sites showed tents and other structures at Everest base camp flattened by rocks and snow. The first reported photo of the avalanche showed a monster "cloud-like" mass of snow and rock descending down the mountain.
Another 100 climbers higher up Everest at camps 1 and 2, were safe but their way back down the mountain was blocked by damage to the treacherous Khumbu icefalls, scene of an avalanche that killed 16 climbers last year. Helicopters had started to shuttle them to base camp, Gavan reported.
"There is a lot of confusion on the mountain. The toll will rise," said Gelu Sherpa, one of the walking wounded among the first 15 injured climbers flown to Kathmandu. "Tents have been blown away," said Sherpa, his head in bandages.
Supplies running out in Kathmandu
The number of casualties is expected to climb as reports come in from far-flung areas, said Home Ministry official Laxmi Dhakal. At least 5,000 people were injured across Nepal.
Tens of thousands of Nepalese who spent the night under a chilly sky, too afraid to return to their damaged homes, were jolted awake by strong aftershocks Sunday, while rescuers aided by international teams cleared rubble in search of survivors.
With the government overwhelmed by the scale of the disaster, India flew in medical supplies and relief crews, while China sent in a 60-strong emergency team. Relief agencies said hospitals in the Kathmandu Valley were overflowing and running out of medical supplies.
Among the capital's landmarks destroyed in the earthquake was the 60-metre (200-foot) Dharahara Tower, built in 1832 for the queen of Nepal, with a viewing balcony that had been open to visitors for the last 10 years.
A jagged stump was all that was left of the lighthouse-like structure. As bodies were pulled from the ruins on Saturday, a policeman said up to 200 people had been trapped inside.
Bodies were still arriving on Sunday morning at one hospital in Kathmandu, where police officer Sudan Shreshtha said his team had brought 166 corpses overnight.
Save the Children's Peter Olyle said hospitals in the Kathmandu Valley were running out of storage room for bodies and emergency supplies. "There is a need for a government decision on bringing in kits from the military," he said from Kathmandu.
Some buildings in Kathmandu toppled like houses of cards, others leaned at precarious angles, and partial collapses exposed living rooms and furniture in place and belongings stacked on shelves.
Rescuers, some wearing face masks to keep out the dust from collapsed buildings, scrambled over mounds of splintered timber and broken bricks in the hope of finding survivors. Some used their bare hands to fill small white buckets with dirt and rock.
Army officer Santosh Nepal and a group of rescuers worked all night to open a passage into a collapsed building in the capital Kathmandu. They had to use pick axes because bulldozers could not get through the ancient city's narrow streets.
"We believe there are still people trapped inside," he told Reuters, pointing at concrete debris and twisted reinforcement rods where a three-storey residential building once stood.
Saturday's magnitude 7.8 earthquake, which was centered outside Kathmandu, the capital, was the worst to hit the poor South Asian nation in over 80 years. It destroyed swaths of the oldest neighborhoods of Kathmandu, and was strong enough to be felt all across parts of India, Bangladesh, China's region of Tibet and Pakistan.