Key facts
- At least 10 people were killed and 17 are missing following a tunnel collapse.
- The incident occurred at the under-construction Teesta hydroelectric project in Sikkim, India.
- A suspected gas explosion is believed to have triggered the collapse.
- Rescue efforts are complicated by the presence of toxic gases within the tunnel.
- Construction accidents are common in India due to rapid infrastructure growth and challenging geological conditions.
At least 10 people were killed and 17 others remain missing after a suspected gas explosion triggered a collapse inside an under-construction tunnel at a hydropower project in India’s northeastern Himalayan state of Sikkim, officials said Tuesday. The blast ripped through the tunnel on Monday at Samardung village, about 40 kilometers (25 miles) from the state capital, Gangtok, where workers were carrying out construction on the 500-megawatt Teesta hydroelectric project. Survivors reported hearing a loud explosion before debris trapped dozens inside. Six officials from the state-owned National Hydroelectric Power Corporation (NHPC), which is building the project, entered the tunnel to assist in rescue efforts but became trapped themselves. "We have recovered 10 bodies so far and 17 others are feared trapped," local police chief Sonam Dolma told reporters. Rescue teams, including the National Disaster Response Force (NDRF), are struggling to reach those trapped due to hazardous conditions inside the tunnel, where toxic gases have accumulated. "We found toxic gases such as methane, carbon monoxide and hydrogen sulphide inside the tunnel," NDRF official Nitin Kumar said, adding that rescuers were using specialized breathing equipment. Construction accidents are not uncommon in India, where rapid infrastructure growth often collides with fragile geology, construction lapses, extreme weather, and safety standards. In the Himalayan region, fragile mountains, seismic activity, and unpredictable underground conditions make tunnel projects especially risky. In 2023, a section of a tunnel in northern Uttarakhand state collapsed, trapping 41 workers for 17 days before their rescue. Experts suggest the Teesta River basin, where the project is located, is in a seismically active region with young, fragile rock formations containing fractures and underground pockets that can trap ancient gases. Dr. Devesh Walia, a geology professor, stated that the area's young rock formations, some associated with coal-bearing strata, could have trapped methane and other gases, potentially triggering an explosion.