A catastrophic flash flood and landslide disaster along the Nepal–China border has killed at least 162 people and left hundreds more missing, as rescue teams continue searching through communities devastated by a massive wall of mud, rock and water.

The disaster struck Wednesday in the Himalayan region near Nepal's border with China's Tibet, sending floodwaters through towns and valleys along the Bhote Koshi and Trishuli river systems. Entire sections of roads, bridges, homes and other infrastructure were swept away as the powerful surge moved downstream. Nepalese officials warned that the death toll could continue to rise as rescue crews reach areas that remained inaccessible after the initial flooding.

The scale of the disaster became clearer Thursday as helicopters were deployed to search for survivors and deliver emergency supplies. Authorities said nearly 1,500 people were missing across Nepal and Tibet, although officials cautioned that some of the figures from the two sides of the border may overlap. Nepal alone reported hundreds of missing people, including large numbers of tourists and pilgrims who had been traveling through the region.

Among those reported missing are nationals from numerous countries. Nepalese tourism officials said the missing included people from India, the United States, Australia, Britain and Canada, among other countries. At least 47 Americans were reported among those missing by Nepalese officials, while dozens of Australian, British and Canadian nationals were also unaccounted for.

The disaster struck an area that serves as both an important transportation corridor and a popular route for trekkers and religious pilgrims. Some of those missing had been traveling toward Mount Kailash and Lake Mansarovar, sacred destinations for millions of Hindus and Buddhists. Others were trekking in the surrounding Himalayan region during a period when roads and mountain communities can become particularly vulnerable to heavy rain, landslides and sudden flooding.

The flooding also caused widespread destruction to critical infrastructure. At least 19 bridges were swept away, while roughly 40 kilometers of roads were damaged or destroyed in Nepal. Hydropower projects were also affected, with officials estimating that approximately 430 megawatts of electricity-generating capacity had been disrupted—more than 12% of Nepal's total hydropower capacity.

The damage has created significant challenges for emergency responders. Roads leading into some of the hardest-hit communities were destroyed, while power and communications systems were disrupted. In some areas, helicopters have had difficulty landing because of dangerous conditions and high water levels, forcing rescue teams to rely on difficult aerial operations and ground searches where access remains possible.

The cause of the disaster has also become clearer. Initial reports suggested that an earthquake may have triggered the event, but subsequent analysis from the U.S. Geological Survey indicated that the seismic signal was associated with a glacial collapse and massive debris flow, rather than a conventional earthquake. An avalanche of ice and rock reportedly entered the Lhende Khola River near the Himalayan border, creating an enormous surge of water, mud and debris that moved rapidly downstream.

Experts say the event highlights the growing risks facing communities in the Himalayan region. The mountains contain some of the world's largest remaining glaciers, but rising temperatures are contributing to changes in glaciers, ice formations and high-altitude lakes. Researchers have warned that the combination of melting ice, unstable mountain slopes, intense rainfall and development in vulnerable valleys can increase the potential for sudden and destructive floods.

The region has experienced similar disasters before. Last year, flooding along the Bhote Koshi River killed people and damaged a major bridge connecting Nepal and China. That disaster was eventually linked to the drainage of a glacial lake in Tibet. Experts say the repeated events demonstrate why early-warning systems and stronger monitoring of glaciers and high-altitude lakes are becoming increasingly important.

The economic damage could also be substantial. Nepal relies heavily on its mountainous transportation networks to connect communities, support tourism and move goods between the country's major population centers and neighboring countries. The destruction of bridges and roads could disrupt commerce for months, while damage to hydropower facilities could place additional pressure on the country's electricity supply.

Tourism is another major concern. Nepal's economy benefits significantly from international visitors who travel to the Himalayas for trekking, mountaineering and religious pilgrimages. The disaster struck in an area used by international travelers, and reports that hundreds of foreign nationals are missing could have a significant impact on tourism confidence and future travel plans.

International governments have begun responding to the crisis. India has offered humanitarian assistance and is coordinating with Nepal on rescue and relief operations. The United States said it was sending a disaster-response adviser and providing $500,000 in assistance for emergency shelter, relief supplies, water, sanitation and hygiene programs. The United Nations has also said that teams and supplies are being mobilized to support affected communities.

Other governments are monitoring the safety of their citizens and coordinating with Nepalese authorities. Australia, Britain, Canada, South Korea, Malaysia and other countries have reported nationals who are missing or potentially affected by the disaster. The international response is expected to grow as authorities determine the full extent of the damage and identify additional people who may be stranded or missing.

For Nepal, the immediate priority remains finding survivors and accounting for those who are missing. Rescue teams are continuing to search through areas covered by mud and debris while emergency personnel work to restore roads, communications and electricity.

The disaster also raises broader questions about how countries can prepare for increasingly dangerous natural hazards in vulnerable mountain environments. Early-warning systems, glacier monitoring, stronger infrastructure and emergency evacuation plans could become increasingly important as climate and environmental conditions change across the Himalayas.

For families waiting for information about loved ones, however, the focus remains much more immediate. Rescue workers are continuing their search while helicopters carry supplies into isolated communities and authorities attempt to reconnect areas cut off by destroyed roads and bridges.

With more than 160 people confirmed dead and hundreds—and potentially more than a thousand—still missing, the Nepal flash flood is developing into one of the region's most devastating disasters in recent years. As search operations continue, officials are warning that the final human and economic toll may not be known for days or even weeks.