At least 10 workers died and more maybe trapped after an under-construction tunnel at a hydroelectric project collapsed in India’s northeastern state of Sikkim.
The tunnel at state-run NHPC Ltd.’s 500-megawatt Teesta-VI project caved in around midday on Monday after a sudden burst of methane gas from the rocks triggered an explosion, the company said said in a stock exchange filing. The blast trapped 25 workers and officials in the tunnel located in Namchi district, it added.
Many workers are still feared to be stuck inside, Deepti Pradhan, a Sikkim government public relations officer, said by phone.
“All possible efforts are being made for evacuation of the trapped personnel,” the company said, adding that it will conduct a detailed probe to find out the cause of the incident.
Following the tragic incident at the under-construction tunnel of the NHPC Teesta Stage VI Hydroelectric Project at Samardung, Jholungey, in Namchi District, Hon’ble Prime Minister Shri Narendra Modi Ji spoke with me to enquire about the situation and the ongoing rescue…
— Prem Singh Tamang (Golay) (@PSTamangGolay) July 21, 2026
Incessant heavy rains over the last few days have triggered several landslides and disrupted connectivity in the Himalayan state, which is located on the border with China.
Extreme and erratic weather events are jeopardizing India’s push to build large infrastructure projects, particularly in the fragile Himalayan region where much of India’s hydropower potential is located. A surge in construction activity in the unstable mountains has caused a spate of landslides, heightening the risks for the country, which is among the most impacted by climate disasters.
The rescue efforts have been complicated by poor visibility as well as the presence of smoke and toxic gases inside the blocked tunnel. Several disaster management personnel experienced dizziness and lost consciousness while attempting to clear the site, the Press Trust of India reported.
Several agencies, including the national and state disaster response forces, are carrying out relief operations at the disaster site.
Copyright 2026 Bloomberg.
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