Several metres of mud covered houses, trees and vehicles in the affected areas. Helicopters continued to airlift survivors throughout the day.Prefer HTon Google A video surfacing on social media of the aerial footage from a rescue operation in Nepal showed the scale of destruction caused by the flash floods, which have killed at least 165 people. More than 800 people remain missing. Aerial visuals from the rescue operation show villages covered in mud, with massive destruction left behind by the flooding.Dozens were swept away, while homes, roads and power projects were destroyed in areas further downstream. The floods have also prompted authorities in Uttar Pradesh and Bihar to remain on high alert. Evacuations are being carried out in vulnerable areas of districts along the border in both states. Follow live updates related to Nepal floods here.Video shows Nepal floods aftermathFloodwaters tore through settlements located along two rivers, Bhote Kosi and Trishuli, in Nepal, destroying houses, roads, bridges and power plants.Aerial visuals from the rescue operation show villages covered in mud, with massive destruction left behind by the flooding. HT could not independently verify the authenticity of the visuals.Notably, the Nepali Army has been conducting rescue flights and has brought several people to safety. Residents living close to the rivers in high-risk areas have also been asked to move to safer locations.Several metres of mud covered houses, trees and vehicles in the affected areas. Helicopters continued to airlift survivors throughout the day.Footage showed houses reduced to rubble, cars being carried away by the water and a metal bridge collapsing into the floodwaters.Witnesses said entire villages were swallowed by the floods. "The settlements next to the river have been completely swept away. Five of my own relatives are missing.” Tula Bahadur BK, a health worker in Rasuwa, told news agency Reuters.ALSO READ | Pictures show trail of destruction in Nepal floods: People trapped in mud, vehicles buried as search on for survivorsRescue, relief operations underwayHelicopters are delivering tents, food and other emergency supplies in the worst-affected districts. The supplies were provided by neighbouring India, Nepali Army spokesperson Raja Ram Basnet said.Notably, India dispatched 10 metric tons of disaster-relief material, including temporary shelters, blankets, hygiene kits, solar lamps and medicines, according to the external affairs ministry.More than 5,000 personnel from the army and police have been deployed for rescue operations and to recover bodies.The US state department said it was sending a disaster response adviser and providing assistance of $500,000.Nepal's national disaster risk reduction and management authority (NDRRMA) said 826 people remained missing. Rescue teams are continuing their search for survivors near the Nepal-China border.What caused the flash floods?The US Geological Survey said on Thursday that a glacial collapse triggered seismic activity, leading to "catastrophic" effects downstream in Nepal and Tibet.The agency said the seismic activity was first thought to have been caused by an earthquake. It was later found to be the result of a glacial collapse and debris flow, which "caused subsequent catastrophic impacts downstream".With inputs from agenciesFollow the latest breaking news, major developments and agenda-setting stories from India and around the world with the newsdesk at Hindustan Times. Operating round the clock, the desk brings together experienced editors, reporters and correspondents to deliver fast, accurate and contextual reporting across subjects that influence public policy, governance, business, society and international affairs.