The collapse occurred after a massive landslide blocked the tunnel entrance, with preliminary reports suggesting a buildup of methane or other toxic gases worsened the disaster. Rescue teams are battling hazardous fumes, low oxygen levels and continuous monsoon rains.
BY PC Bureau
July 21, 2026: A major tragedy unfolded at the under-construction NHPC Teesta Stage VI Hydroelectric Project in Sikkim’s Namchi district after a landslide triggered the partial collapse of a tunnel on Monday afternoon, leaving at least nine workers dead, several injured, and many others still feared trapped.
Confirming the rising death toll on Tuesday, Sikkim Chief Minister Prem Singh Tamang described the incident as one of the state’s worst industrial disasters in recent years and said the government was making every effort to rescue those still trapped inside the tunnel.
The accident occurred at the Samardung tunnel in Jholungey, South Sikkim, where construction work was being carried out by Patel Engineering Limited for the National Hydroelectric Power Corporation (NHPC).
Sikkim NHPC Tunnel Tragedy Update
– Death toll rises to 9 at the NHPC Teesta Stage-VI Hydropower Project in Samardung, Namchi. Rescue teams continue searching for the remaining trapped workers.#Sikkim #NHPC #TunnelCollapse #RescueOperation #ILoveSiliguri pic.twitter.com/6hI4BvCpxe— I Love Siliguri (@ILoveSiliguri) July 21, 2026
Landslide, Toxic Gas and Tunnel Collapse
According to officials, the incident took place between 3 pm and 3.40 pm on Monday when a massive landslide blocked the tunnel entrance. Preliminary investigations suggest the landslide led to the accumulation of methane or other toxic gases inside the tunnel, triggering a blast-like pressure event that caused a section of the under-construction tunnel to collapse.
The collapse filled the tunnel with debris while hazardous gases and low oxygen levels created extremely dangerous conditions for those trapped inside. Rescue personnel entering the tunnel reportedly experienced dizziness and breathing difficulties, forcing authorities to deploy specialised protective equipment.
Casualties and Rescue Operations
Officials said nearly 27 workers were believed to have been inside the tunnel, located around 1.5 to 3 kilometres from the entrance, when the collapse occurred.
As of Tuesday:
- Eight workers have been confirmed dead.
- At least 12 workers have been rescued and shifted to hospitals for treatment.
- More than 18 workers are still feared trapped, although officials said the exact number remains uncertain as rescue teams continue to verify attendance records and assess conditions inside the tunnel.
The bodies of the deceased have been shifted to Singtam District Hospital, STNM Hospital in Gangtok and Namchi District Hospital for post-mortem examinations and identification.
Massive Multi-Agency Rescue Mission
An extensive rescue operation is underway involving the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Sikkim Police, Fire and Emergency Services, Health Department, NHPC officials, and local administration.
Given the presence of toxic gases and depleted oxygen levels, rescuers are using breathing apparatus, gas detectors, oxygen support systems and specialised protective gear before entering the tunnel.
The operation has been further complicated by continuous monsoon rains, which have triggered unstable slopes, poor visibility and the constant risk of fresh landslides around the project site.
Heavy earthmoving machinery is being used to clear debris from the tunnel entrance while engineers assess the structural stability of the remaining sections.
READ: PM Modi Breaks Silence on NEET Leak, Calls It a ‘Grave Sin
PM Modi Assures Full Support
Prime Minister Narendra Modi spoke to Chief Minister Prem Singh Tamang and assured him of the Centre’s full support for the rescue and relief operations.
Union Minister Jyotiraditya M. Scindia also expressed grief over the loss of lives and said the Union government was closely coordinating with the Sikkim administration to ensure all possible assistance.
Chief Minister Tamang directed all departments to prioritise rescue efforts, provide immediate support to the affected families and ensure the best possible medical care for the injured.
Probe Ordered
Authorities are expected to order a detailed investigation into the incident once rescue operations are completed. The probe is likely to examine the role of the landslide, possible methane gas accumulation, geological conditions and adherence to safety protocols at the construction site.
The tragedy has once again highlighted the immense challenges and safety risks associated with executing large-scale infrastructure projects in the fragile Himalayan region, particularly during the monsoon season, when landslides and ground instability become significantly more frequent.
Rescue operations continued through Tuesday evening amid hopes of locating the remaining trapped workers alive.
