Surveillance video verified by AFP shows dozens of people fleeing as a massive wall of debris crashes into the Chinese side of the Nepal-China border area, sweeping trucks and buses aside.
Chinese state media said the disaster caused “major casualties” near a border hub in Tibet, with at least three people confirmed dead and 265 others reported missing.
On the Nepalese side, authorities said at least 95 people had died. Rescue teams searched through thick mud and debris for survivors after floodwaters buried the lower floors of several multi-story buildings.
Nepalese Prime Minister Balendra Shah promised a full government response, saying the state would use all available resources to support those affected by the disaster.
Around 403 tourists were initially unaccounted for, including 341 foreign nationals, according to Nepal’s Ministry of Culture, Tourism and Civil Aviation. The missing included travelers from the United States, India, Malaysia, Britain and Australia, along with 62 Nepalese tourists.
Residents described widespread destruction and trauma. One local man said his relatives had lost their entire home, with three family members rescued while another remained missing.
The exact cause of the disaster was still under investigation. Nepalese Foreign Minister Shishir Khanal said an earthquake may have triggered a landslide that blocked a river before releasing a powerful surge of water downstream.
Nepal’s National Disaster Risk Reduction and Management Authority said satellite imagery from Planet Labs suggested a snow-and-rock landslide near the Nepal-China border may have triggered the flooding.
Experts from the International Centre for Integrated Mountain Development offered a slightly different preliminary assessment. Remote sensing analyst Sarthak Shrestha said there appeared to be no unusual activity originating from the Chinese side and that a rock-and-ice avalanche in Nepal may have blocked the Lhende River, causing the cascading flood.
Images released by Nepalese police showed raging floodwaters sweeping through communities and carrying houses away. Other images showed buildings almost completely buried in mud, with only their upper floors remaining visible.
The Nepalese Army carried out helicopter operations and rescued 114 people from Rasuwa district, one of the areas hardest hit by the disaster. Authorities also urged residents living close to rivers to move to safer ground.
The flooding caused major damage to Nepal’s energy infrastructure. The Nepal Electricity Authority said around 430 megawatts of electricity-generating capacity, including hydropower and solar facilities, had been affected. Transmission and distribution systems were also damaged, disrupting electricity supplies.
Several highways were closed because of flooding and landslide risks.
On the Chinese side, state broadcaster CCTV reported that a mudslide originating in Nepal caused serious casualties and disappearances around Gyirong Port in Tibet. Footage showed fast-moving water carrying branches and debris through flooded roads.
Chinese authorities ordered rescue teams to prioritize finding missing people, treating the injured and reducing further casualties. Traffic officials in Tibet’s Shigatse region also warned that roads remained vulnerable to additional mudslides and were unsafe for travel.
The region has experienced similar disasters before. In July 2025, 17 people were reported missing following a mudslide near Gyirong Port.
Heavy monsoon rains between June and September regularly cause deadly floods and landslides across South Asia, while scientists warn that climate change is making extreme weather events in the Himalayan region more frequent and severe.
Experts also warned that the danger may not be over. Qianggong Zhang of ICIMOD said another flood could occur because a blockage reportedly remains upstream on the border river, potentially allowing another large volume of water to build up and suddenly break through.