The death toll from the massive flash floods along the Nepal-Tibet border rose to 392 on Thursday, as rescue teams waded through mud and raced against time to trace more than 1,400 people still missing, including 290 Indian nationals.
Of the 392 victims, 389 died in the flash floods in Nepal, while three were killed in neighbouring Tibet.
A Nepal Police statement said 796 people, including 50 foreigners, have so far been rescued from affected areas by helicopters, while another 796 have been evacuated by land.
It did not, however, specify the nationalities of the foreigners.
The death toll from the floods has risen to 389, the statement said.
An ice-rock avalanche likely triggered by a glacial collapse near the Nepal-Tibet border sent a torrent of water, mud and debris downstream through central Nepal on Wednesday, devastating towns and villages, washing away homes, vehicles, roads and bridges, and damaging hydropower projects.
A fresh flood threat persisted downstream after a new barrier lake formed near the source of the Bhote Koshi river system, with authorities warning that a possible breach could trigger another surge in the river and downstream areas.
Fears of more potential floods remain, with water trapped by the immense piles of debris blocking the valley.
"With a blockage still lodged upstream on the Nepal-China border river, authorities warn a second flood may occur," said Qianggong Zhang, head of climate and environmental risks at the Kathmandu-based International Centre for Integrated Mountain Development.
Kathmandu's Flood Forecasting Division issued a "special notice" on Thursday, warning of a growing lake behind debris left by the landslide and urging extreme caution.
Nepal authorities reported 910 people missing, as rescuers searched river corridors clogged by mud and debris and families crowded hospitals in a desperate hunt for loved ones.
The disaster also left 558 people missing in Tibet, officials said, taking the number of people reported missing on the two sides of the border to 1,468.
The disaster has also triggered an urgent effort by India to trace its nationals, with the Ministry of External Affairs (MEA) saying 290 Indian nationals remain uncontactable.
New Delhi is making "urgent efforts" to ascertain their whereabouts and coordinate their rescue, the ministry said.
The MEA said 84 Indian nationals had been rescued, including 63 workers employed at the under-construction Trishuli-I run-of-river hydroelectric project and 21 from Tamil Nadu.
Around 200 Indian nationals on the Tibet side have sought assistance for evacuation, the MEA said.
External Affairs Minister S Jaishankar, after a high-level meeting attended virtually by India's envoys in Kathmandu and Beijing, said urgent efforts were underway to ascertain the status and well-being of Indians in the flood-affected areas.
He said the ministry was coordinating with the Nepalese side, other ministries, state governments, tour operators and relevant authorities.
India has also stepped up relief assistance to Nepal. After sending 10 tonnes of Humanitarian Assistance and Disaster Relief (HADR) material on Wednesday, it sent another 37.5 tonnes of HADR material, medicines and food packets on Thursday in a military transport aircraft, taking the total dispatched to 47.5 tonnes.
Chinese authorities estimated that about 2 million cubic metres of water had accumulated in the new barrier lake by Thursday morning, with another 3 million cubic metres potentially flowing into it over the next three days, raising concerns that the natural barrier could breach.
The lake has formed near the confluence of the Chhochen Khola and Purepu Tsangpo rivers, which originate in Tibet and flow into Nepal as part of the Bhote Koshi river system.
Nepal's Department of Hydrology and Meteorology said it had received information from Chinese authorities about the lake and warned of a continuing risk of flooding in the Bhote Koshi and Trishuli river areas. It urged people to stay away from riverbanks and remain in safe places. Travellers, security personnel and search-and-rescue teams were also advised to remain alert.
Chinese authorities are monitoring the lake and carrying out flood simulations and risk assessments. A Chinese rescue team with communications and detection equipment has reached Gyirong to assess the upstream blockage, which officials fear could cause a secondary disaster and complicate ongoing rescue work.
Chinese government officials in Tibet mobilised nearly 800 emergency workers, as well as sniffer dogs and speed boats to help the rescue efforts, the official Xinhua news agency said.
Nepalese security personnel have so far evacuated more than 800 people from affected districts, while helicopters, drones and ground teams continue to search isolated settlements, riverbanks and downstream areas.
The floods first devastated Rasuwa district, about 160 km from capital city Kathmandu, after the ice-rock avalanche and debris flow near the Nepal-Tibet border. A torrent of water, mud, rocks and debris tore through settlements including Timure and Rasuwagadhi before surging downstream through the Bhote Koshi and Trishuli river system.
A preliminary assessment by Nepalese authorities and a revised analysis by the US Geological Survey (USGS) have identified a glacial collapse and debris flow, rather than an earthquake, as the trigger for the disaster.
The ice-rock avalanche struck the Lhende River, temporarily blocking its flow before the natural barrier gave way and unleashed a massive surge downstream into the Bhote Koshi and Trishuli river system.
Nepal's disaster management authority said a debris-laden flood occurred in the Lhende River following an ice-rock landslide near the Nepal-China border, about 20 km northeast of Rasuwagadhi border city. The same flood subsequently entered the Trishuli river after passing through Timure, it said.
The USGS said its analysis of long-period seismic waves showed that the event initially reported as a 4.4-magnitude earthquake was generated by a glacial collapse and debris flow, rather than an earthquake.
Authorities are still assessing the full extent of the destruction.
Nepal's Prime Minister Balendra Shah, who urged the nation to "stand together" hours after the disaster, toured some of the hardest-hit areas on Thursday.
Shah told local authorities to "provide immediate relief to displaced families" and to open blocked roads, his office said in a statement.
Meanwhile, Chinese Premier Li Qiang visited flood-hit Gyirong Township on Thursday to oversee rescue and relief operations. Chinese state media reported that the People's Liberation Army's Western Theatre Command had also sent a directing group to the affected area to coordinate military rescue operations.
Images and videos from the affected areas showed the scale of destruction, with buildings swept away or left standing amid thick deposits of mud and debris, vehicles buried or carried away, roads ripped apart and bridges washed away.
Large stretches of riverbank settlements in Rasuwa and Nuwakot districts were covered in mud, rocks and wreckage.
The Department of Roads in Nepal said the entire 42-km road section between Betrawati in Nuwakot and Rasuwagadhi was damaged at multiple points, while several concrete bridges were washed away.
Nepal's National Disaster Risk Reduction and Management Authority (NDRRMA) said the floods damaged 35 motorable bridges, 45 suspension bridges and about 40 km of black-topped roads, severely disrupting movement across the affected districts.
The Trishuli and Devighat hydropower projects, along with other power infrastructure, were also damaged.
Efforts were underway to reopen the Galchhi-Baireni road in Dhading, which was blocked after the flash floods in Rasuwa. The route is a key link between Kathmandu and other parts of Nepal and serves as an important transit corridor for heavy and light traffic, including during regional blockades and disaster-response operations.
The destruction has severely complicated rescue operations. Security personnel and local authorities have been scouring riverbanks and downstream areas for survivors and recovering bodies carried by the Bhote Koshi and Trishuli rivers.
Nepal Foreign Minister Shisir Khanal on Thursday held telephone conversations with top officials in the US, the UK and several other countries. They expressed solidarity with Nepal and committed to helping the government in its search and rescue works, Khanal's office said.
Nepal Police said 137 bodies have been recovered from Chitwan, the highest number among the affected districts. Bodies have also been recovered from Rasuwa, Nuwakot, Dhading, Gorkha, Tanahun and Nawalparasi districts.
At least 44 Nepali Army personnel, 28 Nepal Police personnel and 13 Armed Police Force personnel are among those whose whereabouts remain unknown, officials said.
Around 160 people working at hydropower projects and customs offices have also been reported missing.
The search has extended to hospitals, where hundreds of relatives have gathered to look for family members and friends missing since Wednesday.
At Tribhuvan University Teaching Hospital in Kathmandu, authorities posted lists of people brought to the facility so families could check whether their relatives had been rescued or were receiving treatment. Photographs of those who died were also displayed, while desks were set up to record details of people whose whereabouts remained unknown.
The scenes were similar at Bharatpur Hospital in Chitwan, where families searched for relatives as authorities struggled to cope with the growing number of bodies and the mortuary was reportedly running out of space.
Officials rescued 27 foreign tourists stranded in Rasuwa on Thursday, including 11 Indians, four South Koreans, two Italians and two US citizens. The nationalities of the remaining eight had not been confirmed by the Nepal Tourism Board. They were airlifted to Kathmandu by the Nepal Army.
Most of the Indian tourists affected were travelling towards Kailash Mansarovar in Tibet or Gosainkunda in Nepal's Bagmati Province.
The disaster could rank among Nepal's deadliest in many years, with rescuers still unable to reach some areas because of damaged roads, washed-away bridges, deep deposits of mud and debris and the continuing risk of further flooding.
(With inputs from PTI, AFP)