Search teams in Nepal, supported by experts from China and India, used controlled explosions Monday to try and reach hundreds of workers trapped inside blocked hydroelectric tunnels following last week's catastrophic flood.An unprecedented torrent of ice, rock, mud and debris carved a trail of destruction through valley towns and villages across Nepal and into neighbouring China on Wednesday, killing more than 900 people and leaving nearly 5,000 missing. The disaster is believed to have been triggered by a glacial collapse.Hundreds of unidentified bodies, swept down from the mountains, have been buried in shallow graves as rapid decomposition set in under the humid conditions of the Himalayan plains.Nepali officials said the focus remains on reaching 933 workers believed to be trapped across 11 hydropower sites, including several working inside approximately half a dozen tunnels in the severely affected Rasuwa and Nuwakot districts.Nepal army personnel work near the Trishuli Hydropower Project site following deadly flash floods and mudslides, in Rasuwa district, Nepal (via REUTERS)Footage and photographs shared by rescue crews showed earth-moving machinery digging through mud and rock under lights in the dark of night, observed by workers. Military personnel used torches inside a large excavation pit to search for entry points into a blocked tunnel.The Nepali army confirmed that search teams were employing controlled blasts, excavators and searchlights to clear mud and water to reach those inside. Rescuers recovered three bodies after entering two tunnels, though other sections remain buried under heavy silt and are still being searched."A large amount of debris has been deposited and that is posing us a big challenge to open the tunnels," Nepali army spokesperson Raja Ram Basnet said. "Our main focus is on opening the tunnels."Official figures released on Monday confirmed 903 deaths in Nepal, with 4,247 people missing, including the 933 workers at the hydropower facilities. On the Chinese side, authorities reported 16 deaths in Gyirong County, with 546 missing.Nepal's foreign ministry stated that around 590 foreign nationals from 39 countries remain missing, though more than 10,000 individuals—including 323 foreign citizens—have been rescued from the flood zone.A rescuer works at the entrance of a tunnel at Chilime Hydropower Plant as rescue operations continue for people trapped inside (Ashish Gurung via REUTERS)The Red Cross estimates that over 90,000 people were likely affected by the disaster, which Chinese authorities have linked to climate change.Nepal has seen a surge in hydropower construction since the turn of the century, attempting to harness Himalayan water resources to tackle chronic domestic power shortages and sell electricity to neighbouring India.Mountain hydropower projects require extensive tunnel networks to carry water across steep terrain, allowing developers to utilise the sharp elevation drop between high-altitude rivers and generating stations to produce electricity.Prime Minister Balendra Shah said the flood was an "unprecedented and devastating natural disaster" and noted that compiling a full assessment of the destruction remains challenging.In Tibet, near a key border crossing with Nepal, Chinese officials said 261 foreign nationals from 23 countries were unaccounted for.The Nepali army said search-and-rescue teams were using controlled blasts, excavators and searchlights to clear water and mud and reach trapped people (Ashish Gurung via REUTERS)On Monday, Chinese foreign ministry spokesperson Guo Jiakun stated that nearly 100 Chinese citizens remained unreachable on the Nepali side.According to state broadcaster CCTV, a Chinese cabinet meeting called for an all-out effort to locate the missing, release authoritative updates, mitigate hidden risks, and enhance emergency response capabilities.Although Nepal stated it did not require general foreign assistance, it requested specialised tunnel rescue expertise from neighbouring India and China.Rescue operations have repeatedly paused due to severe weather and fears over a lake formed along the Nepal-China border, which began spilling into Nepali rivers and threatening secondary flooding.On Monday, CCTV reported that glaciers surrounding an impact crater near the collapse site in Nepal remain at risk of further collapse. Drone footage showed multiple landslide deposits along riverbanks, presenting risks of further blockages and new lakes forming.Nepal army soldiers work during a search and rescue operation near the Trishuli Hydropower Project site (via REUTERS)State media reported that last week's flood was "caused by glacier instability under the long-term effects of global warming".Two Nepali officials told Reuters that Beijing had shared limited information regarding glacier risks and water levels following recent cooperative talks, expressing concern that a lack of data-sharing could hinder future disaster preparedness.The Chinese foreign ministry stated that Beijing has consistently provided Nepal with hydrological and meteorological data and will continue to "strongly support" relief efforts while protecting common interests.