Nepal has been rocked by aftershocks as the death toll from the magnitude 7.8 quake rose to at least 4,000, as aid agencies prepared "massive" humanitarian operations.

Nepal police said on their Facebook page late on Monday evening that over 3,904 deaths had been counted so far, and 7,180 more were reported injured.

In addition, an avalanche caused by the earthquake killed 18 people at Mount Everest's base camp, 61 people were killed in neighboring India, and China reported 25 people died in Tibet.

Al Jazeera's Andrew Simmons, who is reporting from Bhaktapur, said that more people were feared dead in the ancient city, and residents were struggling to dig through the rubble with limited help from the government.

He also reported sporadic fighting among residents of Bhaktapur over supplies of food, water and tents.

Al Jazeera's Sohail Rahman, who is reporting from the capital Kathmandu, also said that "the death toll is expected to rise in the coming hours and days," as rescuers try to reach remote villages that have been inaccessible since the quake hit.

"Many thousands have been left homeless, and people are sleeping out in the open, and it's chilly when the sun sets across the country," he said.

Meanwhile, rescue efforts have intensified in Nepal amid a stream of foreign aid reaching the capital Kathmandu.

The United Nations said it would release $15 million from its central emergency response fund.

The first nations to respond were Nepal's neighbours - India, China, and Pakistan, all of which have been jockeying for influence over the landlocked nation.

Nepal remains closest to India, with which it shares deep political, cultural and religious ties.

Aid experts said disruptions at the airport were likely to continue, slowing the arrival and distribution of vitally needed supplies.

Kipp Branch, senior medical supply officer for the MAP International charity, said the group was putting together an extensive medical supply shipment that would only be sent once it had clearance to land and distribute emergency health supplies intended to support 10,000 people for three months.

PHOTO CAPTION

People take shelter outside in a public place in fear of aftershocks, after a powerful earthquake struck Nepal, in Kathmandu, Nepal, 26 April 2015.

Al-Jazeera