At least 12 workers died when a portion of an under‑construction tunnel collapsed after a sudden methane gas explosion near the 1.5‑km mark inside the tunnel in Sikkim’s Namchi district.
Rescue teams are still searching for 13 other workers who are believed to be trapped 1.5 km underground. The National Disaster Response Force has focused the operation on a 200‑metre area where the lost men are likely to be found.
The tunnel was built to channel water from the Teesta River into a hydropower plant’s turbines, and is part of a larger project operated by the state‑owned National Hydroelectric Power Corporation (NHPC). In its statement, NHPC said the accident was triggered by a “sudden burst of suspected methane gas trapped in the rocks” which caused an explosion that released dense, toxic fumes.
The Sikkim government confirmed the cause as “methane gas combustion.” A natural gas that can become trapped underground, methane ignites in an enclosed space if it comes into contact with an ignition source.
Out of the 27 workers present in the tunnel, two escaped immediately after the blast, while 25 were trapped. Of those 25, 12 bodies have been recovered so far; 13 people remain unaccounted for. Police have identified seven victims; the rest are migrants from West Bengal, Uttarakhand and Assam states. Post‑mortem examinations will determine the exact cause of death.
Chief Minister Prem Singh Tamang has formed a special investigation team to probe the circumstances and will act based on its findings.
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