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A tunnel accident at the under-construction 500 MW NHPC Teesta Stage VI Hydroelectric Project in South Sikkim has claimed the lives of 12 workers, while 13 others remain trapped even as rescue operations continue under hazardous conditions, officials said on July 22, 2026.
The incident occurred on July 20 inside the project’s ADIT-3 tunnel at Samardung in Namchi district, when a suspected methane gas burst filled the tunnel with dense smoke and toxic gases, trapping 25 workers inside. While NHPC and the Sikkim government have attributed the incident to a suspected methane gas burst, officials said the exact cause will be established after a detailed inquiry.
“The rescue operation is still going on. Twelve bodies have been recovered so far, while 13 people remain trapped inside the tunnel,” Deepti Pradhan, District Information Officer (DIO), Namchi, told Down To Earth (DTE). She added that an inquiry into the incident has been ordered, although further details are yet to be shared.
NHPC in a press release issued on July 21 evening, said it had activated its emergency response protocol immediately after the incident and was coordinating rescue efforts with the district administration, the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), local authorities and other emergency agencies. The company said a specialised rescue team from the Directorate General of Mines Safety (DGMS) had also reached the site, while engineering teams were working round the clock to stabilise conditions inside the tunnel and facilitate rescue operations. NHPC said every possible effort was being made to rescue those trapped and that a detailed inquiry would be conducted to ascertain the cause of the incident.
According to the Sikkim government, rescue operations continue under difficult conditions inside the tunnel, where dense smoke and hazardous gases have hampered recovery efforts. The operation involves personnel from the NDRF, SDRF, Sikkim Police, India Reserve Battalion (IRB), the Mines Rescue Team, Fire and Emergency Services, NHPC and other agencies.
Governor Om Prakash Mathur and Chief Minister Prem Singh Tamang visited the site to review rescue and relief efforts. Chief Secretary Ravindra Telang later chaired a high-level meeting with senior officials and rescue agencies, directing authorities to expedite the identification of the deceased, ensure the dignified handover of mortal remains to their families, and speed up compensation. The state government has announced an ex gratia of Rs 4 lakh for the families of each deceased worker and Rs 50,000 as immediate financial assistance for each injured worker.
The 500 MW Teesta Stage VI Hydroelectric Project is a run-of-the-river hydropower project on the Teesta River at Sirwani village in South Sikkim. Originally awarded to Lanco Teesta Hydro Power Limited, the project stalled after the company entered insolvency proceedings. NHPC acquired the project in 2019 through the corporate insolvency resolution process and has since been executing the remaining works.