Nepal is facing one of its worst natural disasters in more than a decade after powerful flash floods and landslides swept through parts of the country and areas near the Nepal-Tibet border. More than 600 people have been killed, according to Nepalese authorities. The number of missing people has also risen sharply, with the National Disaster Risk Reduction and Management Authority reporting 2,426 people missing. Officials are still updating the figures as rescue teams search through damaged villages, roads and riverbanks. The disaster struck on Wednesday after heavy rain triggered massive floods and mudslides. Rivers quickly rose, carrying huge amounts of mud, rocks and debris. Homes, roads and bridges were destroyed, leaving many communities cut off from the rest of the country. Rescue operations have now entered their fourth day, but continuing rain is making the work more difficult. Helicopters are being used to reach people trapped in remote areas, while soldiers and emergency workers are searching through the rubble for survivors. Thousands of people have already been rescued. However, many families are still waiting for information about their loved ones. At least 517 foreign nationals are among those reported missing. Many tourists and pilgrims were travelling through the region when the floods struck, including people heading toward Mount Kailash, a sacred site for Hindus, Buddhists and Jains. The situation is also serious on the Tibetan side of the border. Chinese state media says at least seven people have died there and hundreds remain missing. Rescue workers have had to cross difficult mountain terrain, rivers and landslide areas to reach affected communities. Satellite images show the enormous scale of the destruction. Areas that were once filled with colourful homes, roads and businesses have been covered by mud and water. A hydropower plant along the Trishuli River has also suffered major damage. In Chitwan district, officials said they had recovered 233 bodies, but only four had been identified. Many of the remaining bodies were badly damaged, making identification difficult. Authorities are collecting DNA samples to help families identify their missing relatives. Nepal's government says rebuilding the country could cost between $4 billion and $5 billion. Roads, bridges, homes and hydropower facilities have all been damaged or destroyed. International assistance is also arriving. The United Nations says tens of thousands of households need food and clean drinking water. The European Union, Canada and the United States have announced humanitarian assistance, while aid trucks are continuing to travel toward badly affected areas. Experts warn that the danger has not completely passed. Water and debris remain unstable, and further rain could cause additional floods or landslides. For now, rescue teams are racing against time to find survivors, recover the missing and provide food and shelter to communities devastated by the floods.