A massive rescue operation is underway in South Sikkim after a suspected methane gas explosion triggered a landslide inside an under-construction tunnel linked to the NHPC Teesta Stage-VI Hydroelectric Project, trapping several workers deep underground. Rescue teams are battling hazardous conditions, including toxic gas and low oxygen levels, making the operation extremely challenging.
Methane Explosion Leads to Tunnel Collapse
The incident occurred on Monday afternoon inside the under-construction tunnel at Samardung in Namchi district. According to preliminary information, methane gas had accumulated nearly 1.5 kilometres inside the tunnel during construction work.
Officials believe an attempt to release the trapped gas resulted in an explosion, which triggered a landslide within the tunnel. The collapse blocked the exit route, leaving a number of workers stranded inside. Several labourers managed to escape immediately after hearing a loud blast, while many others remained trapped beyond the collapsed section.
Rescue Teams Face Dangerous Conditions
The rescue mission began soon after the district administration was informed of the accident. Teams from the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Sikkim Police, Fire and Emergency Services and district authorities rushed to the site.
However, rescue efforts have been severely hampered by the presence of methane gas and dangerously low oxygen levels inside the tunnel. Initial attempts by Fire and Emergency Services personnel had to be abandoned after rescuers experienced breathing difficulties. Some members reportedly fell ill due to exposure to toxic fumes.
Specialised NDRF teams later entered the tunnel equipped with protective gear but were also forced to retreat because of the hazardous environment and unstable conditions caused by the landslide.
Number of Trapped Workers Under Verification
Authorities initially estimated that around 17 workers had been trapped. However, after cross-checking attendance records and information provided by the construction company, officials revised the figure to at least 25 workers. Some reports have indicated that the number could be even higher, though authorities have stressed that verification is still in progress.
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District officials said the exact number will only be confirmed after attendance records and worker details are fully reconciled. The identities of those trapped have not yet been officially released.
Administration Monitoring Rescue Round the Clock
Namchi Deputy Commissioner Anupa Tamling said the administration immediately mobilised emergency response agencies after receiving information about the incident. Rescue personnel from Siliguri and Pakyong were alerted, while local police and emergency services were deployed to secure the area.
According to officials, the biggest challenge remains improving ventilation inside the tunnel before rescue teams can safely advance towards the trapped workers. Engineers are simultaneously assessing the structural stability of the collapsed section to avoid further cave-ins during the rescue operation.
Safety Remains Top Priority
Authorities have emphasised that rescuers will not be sent into unsafe conditions until methane concentrations reduce to acceptable levels. Specialised equipment is being used to monitor oxygen levels and detect combustible gases inside the tunnel.
Traffic movement around the project site has also been regulated to facilitate emergency operations, while senior officials from NHPC, district administration and disaster management agencies continue to supervise the rescue effort.
Medical teams and ambulances remain stationed near the site to provide immediate treatment once workers are brought out.
Investigation Likely After Rescue Operation
While the immediate priority remains saving the trapped workers, authorities are expected to launch a detailed investigation into the cause of the methane accumulation and the circumstances that led to the explosion and landslide.
Experts are also likely to examine whether adequate safety measures were in place for handling gas pockets during tunnelling operations. The incident has once again highlighted the significant risks associated with large infrastructure projects in the geologically sensitive Himalayan region.
As rescue teams continue working under extremely difficult conditions, officials remain hopeful that improved ventilation and stabilisation efforts will allow them to safely reach the trapped workers as quickly as possible.
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