Thousands of rescuers have been racing against time to search for missing people as the death toll rose to 16 after a mudslide struck Gyirong Port in southwest China's Xizang Autonomous Region.

A total of 2,141 personnel, 269 rescue vehicles and more than 3,900 sets of equipment have been mobilized for search and rescue operations, with rescuers advancing towards the disaster's core area by land, water and air, according to information released at a news conference in Gyirong County on Sunday.

The mudslide struck on the morning of August 26 after a disaster on the Nepalese side of the border with China, causing 16 deaths and leaving 546 people missing at Gyirong Port as of Sunday morning.

Authorities said they have launched a comprehensive search involving multiple departments to trace those who remain unaccounted for. The latest screening identified 261 missing foreign nationals from 23 countries, including Nepal, India, the United States, Britain, Canada and Australia. Chinese authorities have notified the relevant foreign embassies and consulates.

After several rounds of searches and checks, authorities said no foreign tourists are currently stranded in Gyirong County.

Cause of disaster identified

Officials said at the press conference that the cause of the disaster has now been identified as a glacier collapse and ice-rock avalanche on the southern slope of Lantang Lirung in Nepal, triggered by long-term glacier instability linked to climate warming.

Around 10:52 a.m. on August 26, a glacier at an altitude of about 5,200 meters collapsed, sending ice and rock rapidly down the mountainside. The resulting massive mudslide traveled about 22 kilometers before reaching Gyirong Port at an altitude of around 1,800 meters, according to an assessment by the Chinese Academy of Sciences' Institute of Mountain Hazards and Environment.

Monitoring data showed that the entire process, from the ice-rock avalanche to its impact on Gyirong Port, took only about six to seven minutes.

The mudslide flattened 27 buildings and related facilities across an area of about 0.7 square kilometers.

The mudslide's sudden onset, large flood peak, high speed and extensive destruction reflect the increasingly prominent new characteristics of cryosphere-related hazards on the Qinghai-Xizang Plateau and surrounding regions, as climate warming contributes to glacier instability, authorities said.

Read more: Ice-rock avalanche in Nepal triggered deadly mudslide along China-Nepal border, investigation finds

China's findings have also been echoed by Nepali experts, including Amodmani Dixit, a senior Nepalese geologist and seismologist, and former Nepali ambassador to China Krishna Prasad Oli, also a scholar with extensive research experience in the Qinghai-Xizang Plateau and the Himalayan region.

Why is it so difficult to carry out rescue operations at Gyirong Port?

Rescue teams continued combing through the disaster's core area on Saturday, carrying out grid-based searches amid challenging terrain after the first groups arrived there on Friday afternoon. Footage from the scene showed the Gyirong Port building reduced largely to a skeletal framework, with firefighters carefully searching through the remains.

About 70 firefighters conducted round-the-clock searches in the hardest-hit area while rescue teams in surrounding areas worked in designated sections. Rescuers used life-detection devices, drones and BeiDou navigation equipment to search for missing people.

To support operations in the core area, multiple heavy-lift drones and helicopters were deployed from early Saturday to airlift rescue equipment and supplies to frontline teams.

However, a barrier lake upstream of Gyirong Port has complicated rescue efforts. Tian Bingwei, an associate professor at Sichuan University's Institute of Disaster Reconstruction and Management, said the conditions of the barrier dam required rescue teams to remain alert.

Material brought down from upstream contained large amounts of ice and snow, leaving the barrier dam with high water content and relatively soft ground, Tian said. The ice avalanche that triggered the disaster also left a mixture of ice, rocks, glacial debris, mud and sediment in the barrier lake, making the dam less stable.

The barrier lake naturally began releasing water the previous day, and its risk was considered manageable on Saturday.

The Ministry of Water Resources said its latest monitoring showed the lake's surface area had shrunk by about 21,000 square meters since August 27, with water flowing out naturally and the barrier body largely drained.

Multiple teams continued to monitor the lake around the clock. China Anneng installed slope radar and deployed drones around the barrier lake to track changes in the terrain and water conditions.

The monitoring system is intended to provide timely warnings so rescuers downstream can move to safety if conditions change, allowing search and rescue operations to continue while risks remain under close watch.

Dai Zili, deputy secretary-general of the International Consortium on Geo-disaster Reduction, said the rugged terrain along the China-Nepal border was another major obstacle to rescue efforts. The Nepalese side has relatively flatter terrain in the river valleys, making access easier, while China's Xizang side is at a higher elevation and features more mountains and deep valleys, making it much harder to move personnel and supplies into the area.

Reopening G216 highway

In addition to those already on the ground, other rescue teams continued to advance toward the core area of Gyirong Port on Saturday, laying ropes through difficult terrain to reach key locations for detailed inspections and systematic searches.

With continuous rain swelling the river and increasing the speed of its flow, rescue teams adjusted their approach and focused on reopening the G216 national highway, the only land route to Gyirong Port.

The road has been extensively damaged by the mudslide, with rescue teams working to reopen the final stretch of the route. More than 2.6 kilometers of the damaged road has now been restored, while the remaining section is difficult to access because of the narrow terrain and soft ground. China Anneng has deployed more than 20 pieces of specialized machinery to speed up the work.

The work becomes progressively more demanding as teams advance deeper into the disaster area. Some sections still retain parts of the original roadbed, while farther ahead, the roadbed has been severely washed away, leaving mud and rocks.

On Saturday afternoon, the first batch of steel reinforcement frames sent by the Xizang regional transport authorities reached the site. The frames will be made into steel cages and filled with rocks to form stable structures, which will then be placed along the damaged sections to rebuild a stretch of nearly 1 kilometer of completely washed-out road.

Earlier on Saturday, rescuers said mud-clearing work on the front section had largely been completed, allowing heavy machinery to move in. Construction had advanced to a point near a bend in the river, about 1.8 kilometers from Gyirong Port.

Emergency support stepped up

Following the disaster, the local government in Xizang activated its highest-level natural disaster emergency and relief responses and established emergency rescue and frontline command centers.

China's Ministry of Finance and Ministry of Emergency Management have allocated 120 million yuan (about $16.8 million) for disaster relief and emergency recovery. The National Development and Reform Commission has arranged a further 100 million yuan in support.

Financial and insurance institutions have also rolled out emergency measures. Insurers have introduced initiatives including policy-free claims settlement and non-discriminatory rescue services. Meanwhile, banks have stepped up cash supplies and provided 200 million yuan in emergency cash support to meet the immediate financial needs of affected residents.

As of Saturday, the insurance sector had received claims linked to the disaster, with preliminary estimated losses approaching 100 million yuan.

China, Nepal coordinate rescue efforts

China and Nepal have strengthened coordination on rescue and relief efforts following the disaster.

Chinese Foreign Minister Wang Yi held a phone call with Nepali Foreign Minister Shisir Khanal on Saturday, during which Wang said China is delivering a package of assistance to Nepal, including emergency cash assistance and humanitarian aid.

At the request of Nepal's government, China's Ministry of Emergency Management dispatched five Chinese tunnel experts to Nepal on Saturday. The experts flew by helicopter from Gyirong and arrived in the disaster area at 4:58 p.m. Beijing Time, immediately joining rescue work at a hydropower station tunnel.

Four more Chinese tunnel experts were subsequently sent to Nepal to support tunnel rescue operations.

Nepal and China moved quickly to coordinate rescue and relief efforts after the mudslide, Nepal's Consul General in Lhasa Laxmi Prasad Niraula said.

Speaking to China Media Group (CMG) on Thursday, Niraula said Nepali pilgrims who had traveled through Gyirong Port en route to Mount Kailash had been properly accommodated, with necessary support provided through coordination between the Nepali Consulate General in Lhasa and the government of the Xizang Autonomous Region.

The pilgrims will later return to Nepal via alternative border crossings, while the two sides are also jointly collecting information on those who entered China for pilgrimage through Gyirong Port, he said.

On the Nepalese side, the death toll had risen to 734, with 2,498 people still missing, Nepal's National Disaster Risk Reduction and Management Authority said on Sunday.