A tunnel under construction in Sikkim state, India, collapsed on July 20 or 21 following a suspected methane gas explosion, killing up to 20 workers and trapping others inside the mountain. [1, 2, 3, 4, 5, 6, 7] The tunnel is part of a 500-megawatt hydropower project on the Teesta River developed by the state-owned National Hydroelectric Power Corporation (NHPC). [1, 3, 4, 6]
The explosion released dense smoke and toxic gases such as methane, carbon monoxide and hydrogen sulphide inside the tunnel, producing hazardous conditions that hampered rescue efforts. [1, 3, 4, 5, 6] NHPC said the collapse was triggered by an explosive release of suspected methane gas trapped in rocks inside the tunnel. [6] National Disaster Response Force official Nitin Kumar confirmed the presence of toxic gases impeding rescue operations. [4]
At the time of the accident, between 25 and 27 workers were inside the tunnel nearly 1.5 kilometers into the mountain, with rescue efforts focused on a 200-meter section. [1, 2, 3, 6] Between 9 and 20 workers have been confirmed dead so far; 13 bodies have been recovered as of July 22, with 7 to 8 still trapped, including rescuers. [1, 2, 3, 6, 7] Superintendent of Police Sonam D Bhutia said, “Of the 25 people who were trapped, we have recovered 12 bodies so far, and teams are working to locate the 13 other men.” [1] Rajiv Roka of the Sikkim State Disaster Management Authority estimated about 25-27 were trapped and acknowledged the recovery of 9 to 13 bodies so far. [2, 6]
Victims include migrant workers from West Bengal, Uttarakhand, and Assam, alongside locals from Sikkim. [1] Monsoon rains and waterlogging inside the tunnel have further delayed rescue efforts. [2, 6]
Sikkim Chief Minister Prem Singh Tamang has set up a special investigation team and engaged experts to determine the exact cause of the blast. He said, “We will take action on the basis of the findings.” [1, 7]
Rescue teams continue to work with oxygen equipment to locate and retrieve the trapped workers despite toxic gases and unstable conditions inside the tunnel. [1, 2, 3, 4, 5, 6, 7]
