A young boy trapped on the roof of a house surrounded by raging floodwaters was rescued by the Nepal Army after he used his T-shirt to signal a passing helicopter.A young boy trapped on the roof of a house surrounded by raging floodwaters was rescued by the Nepal Army after he used his T-shirt to signal a passing helicopter.A video of the dramatic rescue showed the child standing on the rooftop and repeatedly waving his T-shirt as a Nepal Army helicopter approached the area.With floodwaters cutting off the house, the boy appeared to have no other way to draw the rescuers' attention. He continued waving until the helicopter hovered over the building.As the helicopter moved closer, the boy reached for its landing skid before grabbing the hand of an army officer seated inside. With the soldier's assistance, he pulled himself up and climbed aboard the helicopter.People watching the operation could be heard applauding and cheering as the child was safely rescued.The rescue came as Nepal continued a massive operation following devastating flash floods and landslides that have killed hundreds of people and left thousands missing.Rescue efforts have increasingly focused on people believed to be trapped inside tunnels at hydropower projects damaged by the floods.Around 10,000 Nepali troops have been deployed for tunnel rescue operations, alongside specialists from China and India, according to Dharam Raj Uprety, chief of Nepal's national disaster management authority.The disaster struck after torrents of ice, rock, mud and debris swept through mountain valleys and rivers on Wednesday, causing widespread destruction along the Nepal-China border.Nepal's disaster authorities said 781 people had died and 2,502 remained missing. More than 90,000 people are believed to have been affected by the disaster.Rescue operations remain underway as authorities work to locate missing people and evacuate those stranded in flood-hit areas.