A suspected gas explosion on Monday triggered a catastrophic tunnel collapse at a hydropower construction site in India’s northeastern Himalayan state of Sikkim, near the Chinese border. Officials confirmed on Tuesday that at least 11 people have died, while 14 others remain missing. The incident occurred at the 500-megawatt Teesta hydroelectric project, situated at Samardung village, approximately 40 kilometers (25 miles) from the state capital, Gangtok.
Sikkim Chief Minister Prem Singh Tamang, who traveled to the disaster site to oversee the situation, stated that the explosion was caused by a build-up of methane gas. According to official reports, at least 27 people were trapped following the blast. While two workers managed to escape, the situation worsened when six officials from the state-owned National Hydroelectric Power Corporation (NHPC)—the organization building the project—entered the tunnel to assist in rescue efforts and subsequently became trapped themselves.
Survivors recounted hearing a loud explosion immediately before debris collapsed, trapping dozens of workers inside the structure. Rescue teams, including members of the National Disaster Response Force (NDRF), are currently working to reach the 14 individuals still missing. However, operations are being severely hampered by hazardous conditions and the presence of toxic gases.
Nitin Kumar, an NDRF official at the scene, confirmed that rescuers are encountering dangerous levels of methane, carbon monoxide, and hydrogen sulfide inside the tunnel. To continue the search for survivors, rescue personnel are required to use specialized breathing equipment to navigate the toxic environment.
Geological experts have highlighted the inherent risks of construction in the Teesta River basin, which is located in a seismically active region. Dr. Devesh Walia, a geology professor at North-Eastern Hill University in Meghalaya, noted that the area consists of relatively young, fragile rock formations that can contain fractures and underground pockets capable of trapping ancient gases. He explained that it is highly probable these accumulated gases triggered the explosion.
The disaster highlights the ongoing challenges of infrastructure development in India, where rapid growth often encounters fragile geology, seismic activity, and safety standard concerns. The Himalayan region is particularly susceptible to such risks. Similar incidents have occurred recently, including a coal mine explosion in Meghalaya in February that killed at least 18 workers, and a 2023 tunnel collapse in Uttarakhand that trapped 41 workers for 17 days before they were successfully rescued.
