At least 546 people have been killed and more than 2,000 remain missing following devastating flash floods and landslides that swept through parts of the Nepal-Tibet border region, triggering a massive search-and-rescue operation, authorities said yesterday.

The disaster struck on Wednesday morning in Nepal’s northern Rasuwa district along the border with Tibet, sending a huge wall of water and debris down the Trishuli River and destroying buildings, bridges and roads. The flooding has caused extensive destruction on both sides of the Nepal-China frontier.

In Nepal, authorities have recovered hundreds of bodies while close to 2000 people remained missing as of yesterday, ABC News quoted the country’s National Disaster Risk Reduction and Management Authority to have revealed.

At least 4,451 people have been rescued or injured, including 129 foreign nationals, while 8,380 police personnel have been deployed to support rescue and recovery operations.

Across the border in Tibet, Chinese state media reported that three people had been confirmed dead and 558 others remained missing, according to local officials.

The number of missing people has fluctuated as rescue teams gain access to areas previously cut off by floodwaters, mudslides and damaged roads.

Among those still unaccounted for are 90 Americans, according to a US State Department spokesperson. Five Americans had been evacuated by Friday, up from three reported the previous day.

The flooding began at about 8:40 a.m. local time Wednesday in the Rasuwa district, inundating communities along the Trishuli River and sweeping away or burying structures in its path.

An analysis of verified video footage and satellite imagery showed that the powerful surge of water and debris caused destruction extending at least 62 miles downstream from the Nepal-Tibet border.

Nepal’s disaster authorities said the flooding was reportedly triggered by a massive landslide about 12 miles northeast of the Rasuwagadhi border post along the Nepal-China frontier.

The United States Geological Survey recorded seismic activity associated with the landslide at magnitude 5.2. The agency initially identified the event as a 4.4-magnitude earthquake before correcting its assessment and confirming that it was caused by the landslide.

Scientists are investigating what triggered the massive slope failure. A Columbia University geophysicist told ABC News that the landslide appeared to have swept away a large glacier, or part of one, in a Himalayan mountain pass.

The initial glacier site was located on a cliff about 16,000 feet above sea level, while the resulting debris avalanche travelled roughly 6,000 feet down the mountain slope, according to the USGS.

USGS research geologist Ben Mirus said more than 100 million cubic metres of ice, rock and debris may have been displaced during the event, although the full scale of the landslide will take time to determine.

The disaster has also left families desperate for information about relatives who remain missing.

Siddarth Venkatachalam, 30, told ABC News that he had spoken with his mother only a few hours before she disappeared while travelling in Nepal with his father and aunt, who are also among the Americans missing.

“They were excited for this trip,” he said, describing it as a spiritual and religious journey for which the family had been preparing for some time.

The family was reportedly located through Life360 on a bridge near the Tibetan border shortly before the devastating flood struck.

Nepal’s Office of the Prime Minister expressed deep sorrow over the loss of life and offered condolences to the families of those killed and missing.

The government has also established an Emergency Control Room to coordinate search and rescue operations, verify information and provide consular assistance to foreign nationals affected by the disaster.

Rescue teams have been using helicopters and other emergency equipment to reach people stranded by the floods, while survivors have been moved to safer locations and temporary camps.

The scale of the destruction has complicated rescue operations, with roads and bridges damaged or washed away and several communities cut off from surrounding areas.

US President Donald Trump, asked about Americans affected by the disaster on Thursday, described the flooding as a “terrible thing” and said Washington was in contact with Nepalese authorities.

“We are sending aid, and we’ve spoken to the leadership and let them know anything they want will happen,” Trump said.

As rescue operations continue, authorities warn that the death toll and number of missing persons could change as teams gain access to isolated communities and recover more victims. (THISDAY, with agency report)