KATHMANDU, Nepal -- Tens of thousands of Nepalese who spent the night under a chilly sky were jolted awake by strong aftershocks Sunday, and rescuers aided by international teams cleared rubble in search of survivors after a powerful earthquake killed at least 1,865 people across the Himalayan region.

Nepal bore the brunt of the quake's impact with at least 1,805 dead and more than 5,000 injured. The toll is expected to climb as more reports come in from far-flung areas, said Home Ministry official Laxmi Dhakal. Among the dead are 17 who were struck by a quake-triggered avalanche on Mount Everest that buried part of the base camp packed with foreign climbers at the end of the climbing season.

Saturday's magnitude 7.8 earthquake, which originated outside the capital Kathmandu, was the worst to hit the poor South Asian nation in over 80 years. It destroyed the old, historic part of Kathmandu, and was strong enough to be felt all across the northern part of neighbouring India, Bangladesh, China's region of Tibet and Pakistan, where a total of 60 people died.

"There were at least three big quakes at night and early morning. How can we feel safe? This is never-ending and everyone is scared and worried," said Sundar Sah. "I hardly got much sleep. I was waking up every few hours and glad that I was alive."

When the earth first shook, residents fled homes and buildings in panic. Walls tumbled, trees swayed, power lines came crashing down and large cracks opened up on streets and walls.

After the chaos of Saturday -- when little organized rescue and relief was seen -- there was relatively more order on Sunday as rescue teams fanned out across the city. At one place, police rescuers were trying to extricate a man lying under a dead person, crushed by a pile of concrete slabs and iron beams. His family members stood nearby, crying and praying.

Police said the man's legs and hips were totally crushed.

"We are digging the debris around him, cutting through concrete and iron beams. We will be able to pull him out but his body under his waist is totally crushed. He is still alive and crying for help. We are going to save him," said police officer Suresh Rai.

Most areas were without power and water Sunday, but with Kathamandu airport reopened, first aid flights began delivering aid supplies. Workers were sending out tents and relief goods in trucks and helicopters, said disaster management official Rameshwar Dangal.

He said that government and private schools have been turned into shelters.

More than two dozen aftershocks jolted the area after the first quake and continued into Sunday. Forecasts called for rain and thunder showers Sunday and the temperatures were in the mid-50s (14 Celsius), cold enough to make camping outside uncomfortable.

Still, thousands of people spent the night at Tudikhel, a vast open ground in the middle of Kathmandu, just next to the old city that is lined with historic buildings and narrow lanes. Now it is in ruins.

"We hardly slept through the night. It was cold and it rained briefly and it was uncomfortable, but I am glad I brought my family out to the open," said Ratna Singh, a vegetable vendor who was huddled under a blanket with his wife and son.

"At least I knew my family was safe. Every time the ground shook at night, I thanked God my family was there with me and safe. I don't think I am going to be sleeping inside the house anytime soon. We are all petrified," he said.

The quake will likely put a huge strain on the resources of this poor country best known for Everest, the highest mountain in the world. The economy of Nepal, a nation of 27.8 million people, relies heavily on tourism, principally trekking and Himalayan mountain climbing.

The world reacted with alacrity to the disaster, offering aid in the form of money, relief material, equipment, expertise and rescue teams.

Among the first to move in was Nepal's giant neighbour India, with which it has close political, cultural and religious ties. Nepal is the world's only Hindu nation, and majority of Indians are Hindus although it does not have an official religion.

Indian air force planes landed Sunday with 43 tons of relief material, including tents and food, and nearly 200 rescuers, India's External Affairs Ministry spokesman Vikas Swarup said. The planes were returning to New Delhi with Indian nationals who were stranded in Kathmandu. More aid flights were planned for Sunday.

Hospitals in the Kathmandu Valley were overcrowded, running out of room for storing dead bodies and running out of emergency supplies, the United Nations said in a statement.

"The reports of the devastation are still coming in and the numbers of people killed, injured and affected by this earthquake continue to rise," U.N. chief Ban Ki-Moon said. "It is clear that very many lives have been lost. There has also been significant damage to Nepal's irreplaceable cultural heritage."

A mountaineering guide, Ang Tshering, said an avalanche after the quake swept base camp where expeditions were preparing to scale Everest, flattening tents and killing at least 17 climbers and guides and leaving an unknown number injured and missing and others cut off. Their nationalities were not immediately known.

The U.S. Geological Survey put the magnitude of the quake at 7.8. It said the quake hit at 11:56 a.m. local time (0611 GMT) at Lamjung, about 80 kilometres (50 miles) northwest of Kathmandu. Its depth was only 11 kilometres (7 miles), the largest shallow quake since the 8.2 temblor off the coast of Chile on April 1, 2014.

The shallower the quake the more destructive power it carries.

The quake occurred at the boundary between the two pieces, or plates, of Earth's crust, one of which supports India to the south and the other Eurasia to the north. The Indian plate is moving northward 45 millimeters (1.7 inches) a year under the Eurasian plate, and this results in earthquakes once every 500 years on an average, said Marin Clark, a geophysicist at University of Michigan, Ann Arbor.

So the quake was "definitely not a surprise," she said. Over millions of years, such quakes have led to the uplift of the Himalayas. Nepal suffered its worst recorded earthquake in 1934, which measured 8.0 and all but destroyed the cities of Kathmandu, Bhaktapur and Patan.

The power of Saturday's tremors brought down several buildings in the centre of the capital, the ancient Old Kathmandu, including centuries-old temples and towers.

Among them was the nine-story Dharahara Tower, one of Kathmandu's landmarks built by Nepal's royal rulers as a watchtower in the 1800s and a UNESCO-recognized historical monument. It was reduced to rubble and there were reports of people trapped underneath.

The Kathmandu Valley is listed as a World Heritage site and is a collection of seven locations around Nepal's capital that reflect the country's rich religious history. The Buddhist stupas, public squares and Hindu temples are some of the most well-known sites in Kathmandu, and now some of the most deeply mourned.

The head of the U.N. cultural agency, Irina Bokova, said in a statement that UNESCO was ready to help Nepal rebuild from "extensive damage, including to historic monuments and buildings of the Kathmandu Valley."

Nepali journalist and author Shiwani Neupane tweeted: "The sadness is sinking in. We have lost our temples, our history, the places we grew up."

- Naqvi reported from New Delhi. Associated Press writers Munir Ahmed in Islamabad, Jan M. Olsen in Copenhagen and Seth Borenstein in Washington, D.C. contributed to this report.