At least nine workers have died and 16 others remain trapped after a suspected methane gas explosion inside an under-construction tunnel of the NHPC Teesta Stage-VI Hydroelectric Project in Sikkim’s Namchi district triggered a landslide that sealed the tunnel entrance.
The incident occurred at around 3.40 pm on Monday at the Samardung tunnel site, where 25 workers, including NHPC personnel and employees of contractor Patel Engineering, were inside during construction. According to officials, methane gas is believed to have accumulated around 1.5 kilometres inside the tunnel before an attempt to vent it reportedly triggered an explosion, causing debris to block the escape route.
Rescue operations have entered their second day, with teams from the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Sikkim Police, Fire and Emergency Services, NHPC, the Health Department and the Sikkim State Disaster Management Authority (SSDMA) battling hazardous methane levels, low oxygen, poor visibility and the constant threat of further collapses.
Prime Minister Narendra Modi has spoken to Sikkim Chief Minister Prem Singh Tamang, assuring the state of all possible assistance from the Centre, while officials say saving the remaining trapped workers remains the immediate priority. Authorities have also clarified that the exact cause of the explosion will only be confirmed after a detailed technical investigation once rescue operations are complete.
Hazardous Rescue Underway
The rescue mission has become one of the most technically demanding emergency operations in recent years due to the dangerous conditions inside the tunnel. Officials said methane gas had likely accumulated naturally from underground rock formations encountered during excavation.
Rescue personnel believe an attempt to release the trapped gas may have ignited it, triggering an explosion that caused a landslide inside the tunnel and blocked the passage. While several workers near the entrance managed to escape immediately after the blast, others working deeper underground were cut off from the exit.
The Namchi District Administration received information about the incident at around 3.40 pm on Monday, following which emergency teams rushed to the site. However, initial rescue attempts by the Fire and Emergency Services had to be abandoned after responders experienced breathing difficulties because of high methane concentrations and critically low oxygen levels.
Several rescuers reportedly fell ill during the operation. Subsequent efforts by NDRF teams were also slowed by the hazardous atmosphere, prompting authorities to deploy specialised personnel equipped with gas-protective equipment from neighbouring West Bengal. Additional teams from the NDRF’s 2nd Battalion based in Pakyong and Siliguri have since joined the operation.
Officials involved in the rescue said every metre inside the tunnel presents fresh risks due to unstable debris, narrow access passages and the possibility of secondary collapses. The Namchi District Administration, NHPC officials, SSDMA and multiple emergency agencies have continued operations through the night in the hope of reaching the trapped workers safely.
Prime Minister Narendra Modi on Tuesday spoke with Chief Minister Prem Singh Tamang to review the rescue efforts. According to the Chief Minister, the Prime Minister expressed concern for the affected workers and their families and assured all possible support from the Central Government. The state government has said that every available resource is being deployed to assist the ongoing rescue effort.
Questions Over Tunnel Safety
The accident occurred inside the under-construction tunnel of the NHPC Teesta Stage-VI Hydroelectric Project, a major hydropower project in Sikkim. The tunnel is being constructed by Patel Engineering for NHPC as part of the infrastructure required for the hydroelectric project. Although officials suspect methane accumulation triggered the explosion, they have emphasised that the exact sequence of events will only be established after a formal investigation.
Experts involved in tunnel construction note that naturally occurring methane can be released while excavating through certain underground rock formations. If the gas accumulates in confined spaces without adequate ventilation, it can become highly combustible and ignite when exposed to a spark or ignition source.
Investigators are expected to examine ventilation systems, gas monitoring protocols, emergency preparedness, construction practices and overall safety procedures once the site is declared safe.
Authorities have also acknowledged that casualty figures changed during the initial hours of the incident as attendance records were verified and rescue teams assessed the situation. The latest official update confirms nine deaths and at least 16 workers still trapped, though these numbers may change as rescue operations continue.
The tragedy has once again drawn attention to occupational safety standards in large infrastructure projects, particularly those involving underground construction in geologically challenging terrain. Experts say tunnelling projects require continuous gas monitoring, robust ventilation systems and carefully planned evacuation procedures to minimise the risks posed by naturally occurring gases and unstable rock formations.
The Logical Indian’s Perspective
The Sikkim tunnel tragedy is a stark reminder that behind every major infrastructure project are workers who often face invisible risks in pursuit of development. While the immediate focus must remain on rescuing those still trapped and supporting the grieving families, this incident also raises broader questions about workplace safety, emergency preparedness and accountability in high-risk construction environments.
Every worker deserves to return home safely at the end of the day, and tragedies such as these underscore the importance of rigorous safety protocols, transparent investigations and continuous oversight, especially in projects involving hazardous underground conditions.
