NAMCHI, Sikkim – A suspected methane gas explosion caused a tunnel collapse at an under-construction National Hydroelectric Power Corporation (NHPC) project in Sikkim’s Namchi district, killing at least 10 people. Rescue operations are ongoing, with 15 individuals still feared trapped inside the tunnel. The incident occurred on Monday, July 20, 2026, at the NHPC Teesta Stage VI Hydroelectric Project in Samardung, Jholungey.
Hazardous Conditions Hamper Rescue Efforts
Authorities recovered 10 bodies by Tuesday morning. Rescuers, including teams from the National Disaster Response Force (NDRF), face extremely dangerous conditions deep inside the tunnel. Toxic gases like methane, carbon monoxide, and hydrogen sulfide have accumulated, making it difficult for personnel to operate. An NDRF official, Nitin Kumar, stated that rescuers are using specialized breathing equipment and can only enter the site for short shifts, about 15 minutes at a time, due to the hazardous air. Some disaster management personnel have experienced dizziness and lost consciousness during their attempts to clear the site.[m+5]
Sikkim Chief Minister Prem Singh Tamang visited the site and confirmed the explosion was likely caused by a buildup of methane gas. Preliminary investigations suggest the blast may have happened when workers tried to vent naturally occurring methane gas from within the tunnel. This explosion then triggered a landslide, blocking a section of the tunnel and trapping workers inside.[insurancejournal+3]
Project Details and Regional Challenges
The collapsed tunnel is part of the 500-megawatt Teesta Stage VI Hydroelectric Project. Reports indicate 25 workers, including project officials, were initially trapped inside the ADIT-3 tunnel. Twoworkers managed to escape the blast, which survivors described as a loud explosion followed by debris crashing down. Sixpower utility officials who entered the tunnel to assist in the initial rescue efforts also became trapped.[wboc+8]
Construction projects in the Himalayan region often face significant geological challenges. The young, fragile rock formations, high tectonic activity, and extreme stress conditions make tunneling especially risky. Landslides, frequent heavy rainfall, and seismic activity further complicate infrastructure development in Sikkim. These factors contribute to tunnel stability problems, including squeezing ground behavior and rock bursts.[washingtonpost+7]
National Response and Ongoing Efforts
Prime Minister Narendra Modi spoke with Chief Minister Prem Singh Tamang to inquire about the situation and review ongoing rescue operations. Modi assured the state government of all possible assistance from the central government. Multiple agencies, including national and state disaster response forces, are coordinating efforts at the disaster site. Specialized teams trained in mining accidents have also been brought in to aid the rescuers. Incessant heavy rains in recent days have caused several landslides, disrupting connectivity in the Himalayan state and further hindering rescue efforts. Authorities are exploring methods to improve ventilation and stabilize the tunnel before attempting further rescue.[turkiyetoday+7]
The incident highlights the inherent dangers of large-scale infrastructure projects in the geologically sensitive Himalayan region. Efforts continue around the clock to locate and evacuate the remaining trapped individuals.[indiatodayne+2]
