Correction, April 28, 2015: An earlier version of this article said that many locals were camping out in Nagpuri Park, huddling under blankets. The correct location is Nandakishore Park in Naxal, central Kathmandu.

Nepal's prime minister has warned that the number of people killed in the country's worst earthquake in decades could reach 10,000.

Sushil Koirala's comment on Tuesday came as rescuers in Nepal were struggling to reach remote communities.

With the UN estimating eight million people have been hit by the disaster, Koirala said getting help to some of the worst affected areas was a "major challenge".

He said authorities were overwhelmed by appeals for help from remote Himalayan villages left devastated by Saturday's 7.8-magnitude quake.

Mass cremations took place overnight after the government ordered the continuous burning of the bodies to prevent the spread of diseases.

Laxmi Prasad Dhakal, home ministry spokesperson, said on Tuesday the official death toll had risen to about 4,700, with more than 9,000 known to have been injured.

In places like Kathmandu's Basantapur Durbar Square, rescue teams were scrambling to clear the debris to find bodies and possibly survivors trapped underneath.

Heavy rain in Kathmandu was hampering rescue efforts and also adding to the suffering of those made homeless by the quake or sleeping out in the open in fear of aftershocks.

Al Jazeera's Annette Ekin, reporting from Kathmandu, said many locals were camping out in Nandakishore Park in Naxal, central Kathmandu, huddling under blankets. But despite the loss of life and property around them, most people remained calm.

"There's no one they can blame for this, so people are in pretty good spirits," she said.

"Some musicians are camped out in the park, playing the guitar."

Many spent the night in tents, returning only briefly to their homes to pick up supplies.

With fears rising of food and water shortages, Nepalis were rushing to stores and petrol stations to stock up on essential supplies in Kathmandu.

Major hurdle

The size of Kathmandu's airport is a major hurdle to bring in aid, as only planes of a certain size can land on the single runway.

Three days after the quake hit, rescue teams have still not reached some of the worst-affected areas of Lamjung, the site of the quake's epicentre, around 77km west of Kathmandu.

"The situation here is not good. So many have lost their homes. They don't have enough water or food," said Udav Prasad Timilsina, head official in the neighbouring district of Gorkha.

"We haven't even been able to treat the injured. We are in urgent need of essentials like food, water ... and medicines and tents. Rescuers are coming in, but we need help."

In Kathmandu, hospitals were working non-stop, running dangerously low on blood.

Youths were volunteering in hospitals and also as first-aid responders and to clear debris.

In another development, mountaineers reporting from the Everest base camp said on Tuesday all of the climbers who had been stranded at camps by avalanches had been removed to safety.

Taking advantage of Monday's clear weather, three helicopters shuttled climbers all day from camp 1, above the impassable Khumbu glacier, while others trekked back from camp 2 to be airlifted out.

Around half of the tents at the base camp were destroyed by an avalanche unleashed by Saturday's earthquake, killing between 17 and 22 climbers, according to separate accounts.

Around 350 foreign climbers, and double the number of local sherpa guides, had been on the 29,035ft mountain when the worst ever disaster on the world's tallest peak struck.

Three helicopters shuttled 170 climbers from camp 1 to the base camp on Monday. Because of the high altitude and thin air, the aircraft were only able to carry two climbers at a time.

Outside of Nepal, 73 people died in India. The toll in China's far western region of Tibet, which neighbours Nepal, rose to 25, the official Xinhua news agency said, citing the area's disaster relief headquarters.

With additional reporting by Juliette Rousselot in Kathmandu.