Rescuers struggled Monday through mud and debris for a sixth day, as the number of missing people soared to nearly 5,000 since tsunami-like glacial floods roared down from the China-Nepal border, creating an "unimaginable" disaster.
The latest confirmed death toll surged above 900, but the number of those unaccounted for is also climbing -- with unidentified bodies buried in mass graves after DNA sampling.
The huge wave of freezing water, rocks and debris that smashed into villages and towns on Wednesday killed at least 903 people in Nepal and in Tibet, in China, with at least 17 bodies pulled from rivers downstream in India.
Late Sunday Nepali Prime Minster Balendra Shah called the disaster "unimaginable and heartbreaking".
Rescue teams are in a race against time in treacherous conditions in a bid to free dozens of hydropower workers believed trapped in tunnels -- digging, drilling and blasting through debris, a non-stop effort supported by teams from China, India and South Korea.
So far, three dead bodies have been pulled out of two tunnels, and the teams have found routes blocked with mud.
Amid the horror, there has been some hope; a six-year-old pulled out of the mud four days after the disaster on Friday was reunited with her parents after police found her crying for her mother.
"Her body was trapped in mud, but her head was outside," Nepali Armed Police spokesman Netra Bahadur Karki told AFP.
"She is out of danger and recovering at a hospital and has reunited with her family."
- 'Changing climate' -
The disaster was sparked by a glacial collapse, the US Geological Survey said. While the exact cause of that collapse is unclear, climate change is causing glaciers to melt worldwide, raising the risk of such disasters.
Nepali Foreign Minister Shisir Khanal said: "The people of Nepal are one of the major victims of the changing climate and its impact."
Scientists say the Himalayas, the world's highest mountain range, are melting faster as global temperatures rise.
Aid needs are enormous. Entire communities have been swept away, leaving families homeless in heavy rain or sheltering in temporary facilities.
"This is an unfolding disaster," UN children's fund official Abiodun Banire told AFP, saying the needs of the tens of thousands impacted were vast.
Roads have been washed away, power plants destroyed and dozens of bridges smashed.
"We are continuing to work for search, rescue and relief operations," Karki told AFP on Monday, as communications slowly improved. Police initially had to use drones to carry messages into cut-off areas.
"Rescue teams have now reached most areas, by road or by helicopters," he added.
- 'No response' -
With mortuaries overflowing with the dead, Nepal has begun burying some of the hundreds of bodies recovered after taking DNA samples so families can later retrieve them.
Kathmandu has appealed for international support, saying Nepal needed "more than a thousand" freezer units to store bodies.
Distraught families, desperate for news of missing relatives, are watching images of bodies on screens at community centres in a bid to identify the dead.
Shobha Adhikary, in the southern Nepali city of Bharatpur, told a local coordinator she believed one image showed her childhood best friend.
"It looks like him, for sure," she said, showing a photograph of a smiling, middle-aged man.
"My husband and I are best friends with Rajkumar and his wife Geeta," she said. Geeta has also been missing since Wednesday.
Among Nepal's list of the missing are 592 foreigners, including tourists who had come for trekking in its apparently serene mountains, and Hindu pilgrims seeking spiritual peace at Tibet's sacred Mount Kailash.
Nepali army rescuers said Monday its teams were working to "clear water, mud and sediment" as they dug to reach around 100 workers that the government believes may be alive inside multiple tunnels.
They are among the 933 workers at hydropower plants unaccounted for in Nepal. Workers who managed to get out described horrifying scenes when the disaster struck.
At the Upper Trishuli 3A site, rescuers broke through into the upper part of a mud-swamped tunnel, pumping air inside, then using drilling and excavator machines to dig down.
"When members of the team descended using ropes and called out to those inside, there was no response," Shah said, adding that the rescue operation was continuing.
- 'Billions of dollars' -
In China, Tibet is largely inaccessible to foreign journalists, and Chinese authorities are the only source of information.
More than 2,000 personnel are part of rescue operations there, but they have faced intense challenges.
Rescuers trying to reach the epicentre of the disaster, Gyirong Port, only advanced 285 metres on Sunday, according to state media.
The glacial collapse caused the formation of huge lakes dammed by unstable debris, posing a further threat to rescue teams.
China has said 16 people died in Tibet, with 546 people missing.
In Nepal, the disaster agency raised the total number of people missing on its side of the border to 4,247, with 903 bodies recovered.
Nepal's economy is already under pressure, and foreign governments have pledged millions of dollars in humanitarian aid.
Kathmandu warns that the reconstruction bill could run into "billions of dollars".
