At least 160 people have been killed and hundreds remain missing after devastating flash floods swept through communities along the Nepal–Tibet border on Wednesday.
Authorities in Nepal confirmed at least 157 deaths, while Chinese state broadcaster CCTV reported three fatalities and 265 people missing in Gyirong County in Tibet, near the border. Experts believe the disaster was caused by a glacial collapse in the rapidly warming Himalayan region.
Drone footage showed roads torn apart and buildings buried beneath thick, cement-coloured floodwater. China’s state-run Xinhua news agency reported significant casualties as rescue teams attempted to reach affected communities.
The region’s steep valleys serve as important economic routes and travel corridors but are particularly vulnerable when natural disasters strike. Images from Nepal’s badly affected Nuwakot district showed buildings coated in mud up to their second floors, vehicles buried beneath debris and survivors covered in sludge.
Residents said the flood arrived with little warning, leaving communities almost no time to escape.
“When I reached Dhunge bazaar, in half an hour, the flood came and damaged all the market. People were preparing to go to office then,” resident Shoyam Rajbhandari said. “How many people are missing or dead, we don’t know.”
Nepalese officials said 403 people remained unaccounted for, including 341 foreign nationals. Tourism board spokesperson Sunil Sharma said 133 Indian citizens were among those missing while travelling to Mount Kailash in Tibet, a sacred pilgrimage destination for Hindus.
The missing foreigners also included 47 Americans, 34 Australians, 33 British nationals and 24 Canadians. The US State Department said it was aware that American citizens had been affected.
At least 62 Nepalese citizens were also missing among hundreds of people trekking near Gosaikunda Lake in Rasuwa district, which borders Tibet’s Gyirong County. Their journey coincided with the Janai Purnima festival on Friday.
Although Nepal’s monsoon season is generally considered unsuitable for trekking, it remains a major period for pilgrimages to Mount Kailash, with many travellers passing through Rasuwa district.
Nepal police spokesperson Abi Narayan Kafle said at least 28 police officers were among those missing.
Authorities warned residents across several districts to stay away from the Trishuli, Bhotekoshi and Narayani rivers. At least 19 bridges and almost 40 kilometres of road were swept away.
The Bhotekoshi River began flooding at around 9am on Wednesday, destroying several villages and damaging hydropower projects, officials said.
“We have asked both India and China to help us with the rescue efforts,” said government spokesperson Sasmit Pokharel.
The US Geological Survey initially detected what appeared to be a magnitude 4.4 earthquake about 66 kilometres north of Kathmandu, close to the Chinese border.
However, the agency later revised its assessment and concluded that the seismic activity had been caused by a magnitude 5.2 glacial collapse rather than an earthquake. The collapse sent a catastrophic flow of debris downstream towards nearby communities.
The USGS said its conclusion was based on information from nearby seismic stations, long-period seismic waves and satellite imagery.
Several governments have expressed concern over citizens believed to be in the affected region. South Korean officials said nine nationals working on a hydropower project in Nepal were among those reported missing.
Malaysia’s foreign ministry said travel agencies had lost contact with 11 Malaysian citizens believed to be in Rasuwa district. Russia’s embassy in Nepal also reported that four Russian nationals thought to have been in the area were missing.
Indian Prime Minister Narendra Modi spoke with Nepalese Prime Minister Balendra Shah and offered assistance with rescue and relief operations.
“India is prepared to provide Nepal with all possible types of humanitarian assistance. Our teams are closely coordinating on rescue and relief efforts,” Modi said on social media.
Several United Nations agencies were also preparing to provide emergency assistance “in an effort to meet what will clearly be massive humanitarian need,” UN spokesperson Stephane Dujarric said.
Australia, Britain, the European Union, Finland, France, Norway and Switzerland issued a joint statement expressing solidarity with those affected.
“We encourage all those in affected areas to follow the guidance of local authorities and official safety advisories as the situation continues to evolve.”
Climate experts at the Kathmandu-based International Centre for Integrated Mountain Development said an avalanche involving glacial ice and rock was the likely cause of the floods.
“Hydrological observations indicate the exceptional speed and magnitude of the flood wave,” the organisation said, adding that water levels at one point along the Trishuli River rose by as much as nine metres within 30 minutes.
Experts said the most severe flooding occurred along the Lhende Khola River, a tributary of the Bhotekoshi.
“The Lhende Khola has flooded twice in 14 months, this time triggered by an ice rock avalanche from a glacier on the Nepal side that blocked the river and released a sudden surge downstream,” said Saswata Sanyal, a disaster risk reduction specialist at the climate research organisation.
He stressed the importance of effective early-warning systems in “a warming Himalaya.”
The same region experienced similar flash floods in August last year after high temperatures caused a glacial lake in Tibet to overflow. Nine people were killed, while major infrastructure—including a bridge connecting Nepal and China—was damaged.
The Himalayan mountain range stretches across several South Asian countries and contains many of the world’s tallest mountains and remaining glaciers. Its steep slopes and valleys are particularly susceptible to floods and landslides.
Extreme weather events, including intense monsoon rainfall and rapidly melting glaciers, have become increasingly common as global temperatures rise because of human-caused climate change.
Research published in Kathmandu earlier this year found that glaciers across the Hindu Kush Himalaya region are melting at an accelerating rate, with the pace of ice loss doubling since 2000.
