KATHMANDU/BEIJING: At least 177 people have been confirmed dead, and hundreds of locals, tourists and other travellers were reported missing as a huge wall of mud, rocks and water swept into a river along the Himalayan border between Nepal and China's Tibet on August 26, causing severe flooding.

The disaster is still unfolding, and authorities on both sides warned that the final number of casualties could be much higher. The number of missing as of Thursday hit 1,300. Verified videos showed dozens of people being swept away by the fast-moving floodwaters near the border.

Homes, roads and power projects were destroyed in Nepal. In Tibet, officials warned of "major casualties" after a mudslide struck a border crossing in Gyirong county, with several people reported missing.

Nepal's Foreign Minister Shisir Khanal told parliament that an earthquake in the area may have triggered an avalanche, which then caused the flooding, according to local media reports.

Officials in Nepal said at least 341 foreign nationals are among the missing. Sunil Sharma, a tourism board spokesperson, said 133 were from India on pilgrimage to Mount Kailash in Tibet, a sacred site for Hindus. Also missing were 47 from the United States, 34 from Australia, 33 from Britain and 24 from Canada, he said

Flood warnings were issued in India's northern states of Uttar Pradesh and Bihar. Both states border Nepal, and several rivers flowing down from the Himalayan mountains eventually enter the Indian plains.

Security camera footage from the Chinese side of the Nepal-Tibet border showed people running to safety shortly before a massive flow of rocks, mud and water struck buildings and vehicles. The force of the flood destroyed structures and swept away people.

Earthquake Occurred 7 Minutes Before Mudslide

The exact cause of the mudslide was not immediately known. However, the German Research Center for Geosciences said a magnitude 4.4 earthquake had occurred about seven minutes before the time shown on the security footage.

Qianggong Zhang, head of climate and environmental risks at the Kathmandu-based International Center for Integrated Mountain Development, said an ice-and-rock avalanche into the Lhende Khola river on the Nepali side may have triggered the disaster. He said the exact cause had not yet been confirmed.

"With a blockage still lodged upstream on the Nepal-China border river, authorities warn a second flood may occur," Qianggong said.

Rescue helicopters were unable to land in the worst-hit areas of Syapru Besi and Timure in Nepal's mountainous Rasuwa district. The district has a population of about 50,000. Officials said the river was running far above its normal level, making rescue operations difficult.

Television footage showed homes collapsing into the floodwaters, cars being carried away and a metal bridge being swept downstream. Witnesses told Reuters that entire villages had been flooded.

Rasuwa district administrator Narendra Pariyar warned that the disaster could cause heavy loss of life and property. He urged people living along the Bhote Koshi river to move to higher ground after reports that villages and project sites had been destroyed.

Health worker Tula Bahadur BK, who was in Rasuwa, described the scale of the destruction. He said settlements beside the river had been completely washed away, and that five of his relatives were missing.

China's Gyirong Port Hit

China's state news agency Xinhua reported that the mudslide began on the Nepali side and later reached the Gyirong port. The disaster damaged roads, communication networks and electricity links in the Shigatse region near the border.

Chinese state broadcaster CCTV reported that authorities had sent at least 574 rescuers to the Gyirong border crossing.

One rescuer told CCTV that it could take at least four hours for the team to reach the affected area because paths were blocked by sediment up to 1.5 meters, or about five feet, deep. The rescuer said debris had moved upstream from the Nepali side of the border crossing.

Chinese President Xi Jinping ordered an "all-out" search for missing people and called for stronger monitoring and early warning systems to reduce the risk of further disasters.

Nepal's Energy Ministry said about 430 megawatts of electricity supply had been affected, mainly because of damage to hydroelectric projects. A Reuters calculation showed that this represented more than 12 percent of Nepal's total hydropower capacity of 3.2 gigawatts.

Nepal's Prime Minister Balendra Shah said police and the military had joined rescue operations. He said authorities had ordered residents in low-lying areas to move to safer locations and urged people living along the river to remain alert.

Indian Prime Minister Narendra Modi said India was ready to provide all possible humanitarian assistance. He also said teams from India and Nepal were working closely together on rescue and relief operations. An aircraft with relief supplies was ready to take off at short notice for Nepal.

The Bhote Koshi river begins in Tibet and flows into Nepal's Trishuli river. The Trishuli eventually enters India, where it becomes part of the Gandak river system.