Nepal is scrambling to save thousands of people who remain buried under rubble following its worst earthquake in decades, as dozens of aftershocks continue to rumble around the quake's epicentre near the nation's capital.

On Saturday the Nepalese government declared a state of emergency after a 7.8-magnitude earthquake struck the Himalayan nation, killing hundreds of people and touching off a deadly avalanche on Mount Everest.

Officials said that so far more than 1,805 people were known to have died in the powerful quake that struck 80km east of Pokhara on Saturday, about halfway between the town and the capital Kathmandu.

The aftershocks continued into the night, and the toll was expected to rise significantly as the scale of the disaster became clear.

Brian Baptie, of the British Geological Survey, told Al Jazeera on Sunday that aftershocks of a magnitude of up to 6.8 - large quakes in their own right - could continue rumbling in the area "for many weeks".

Emergency workers and army and police personnel, with the help of residents and bystanders, continued to work tirelessly throughout Saturday night to clear the rubble from these sites and to rescue any survivors from under the debris, although bodies were mostly being pulled out.

As night fell in the country of 27 million, tens of thousands of people stayed outdoors in fear that subsequent aftershocks may cause further damage.


Images of devastation: Nepal's earthquake destruction


Of the bodies retrieved so far, 634 were reported dead in the Kathmandu valley and at least 300 more in the capital, a police spokesman told Reuters news agency.

A further 36 fatalities were reported in northern India, 12 in Tibet and four in Bangladesh.

Photos posted on Twitter showed buildings left in rubble, large cracks along roads and worried residents on the streets.

The earthquake destroyed many historical landmarks, including the UNESCO World Heritage temples at Basantapur Durbar Square and the Dharara tower, both in central Kathmandu.

It has been reported that around 250 people may have been in the Dharara tower when it collapsed.

The Kathmandu valley is densely populated with nearly 2.5 million people and poorly enforced building regulations.

Al Jazeera's Subina Shrestha, reporting from Kathmandu, said the worst-affected area of the capital was old Kathmandu, the site of several ancient temples.

Relief agencies have already warned that as many as six million people might be affected by the disaster.

Aid from India and Sri Lanka was already en route overnight.

Everest's peak season

Meanwhile, an avalanche swept a mountain near the Everest base camp, killing at least 17 people and leaving many climbers buried.

British mountaineer Kenton Cool told Al Jazeera that the quake couldn't have come at a worse time, as it was peak climbing season at the base camp and "there are probably 1,000 people or so there". Cool said conditions for rescuers would also be difficult in poor weather conditions.

"This terrible, terrible situation has occurred at exactly the wrong time in terms of human fatality," Cool said.

"Knowing the geology and the lay of the land there, to facilitate the medical care required and to try to medivac people out of there is going to be extremely difficult, especially considering the weather conditions there right now." 

The powerful quake also triggered an avalanche that swept across Everest Base Camp [AzimAfif/AP]

The US Geological Survey said the quake hit at 11:56am local time (06:11 GMT). It initially reported a magnitude of 7.7 before revising its calculation to 7.5, 7.9 and then later, 7.8.

Tremors were felt in a number of India's northern cities, witnesses said. Al Jazeera's reporters in New Delhi said the tremors were also felt across the Indian capital.

Indian officials told the Associated Press news agency that at least 34 people were killed in the Bihar and Uttar Pradesh state.

Al Jazeera's Maher Sattar in Dhaka, Bangladesh, reported that at least three people were killed there, including one who was killed following a stampede triggered by the quake.

Laxman Singh Rathore, director-general of the Indian Meteorological Department, said that the impact had been felt across large swaths of northern India.

"The intensity was felt in entire north India. More intense shocks were felt in eastern UP [Uttar Pradesh] and Bihar, equally strong in sub-Himalayan West Bengal, Sikkim," he said.

(Additional reporting by Juliette Rousselot in Kathmandu)

Volunteers help with rescue work at the site of a building that collapsed after an earthquake in Kathmandu [AP Photo]

Source: Al Jazeera and agencies