Sudden release of suspected methane gas killed 12 workers, and 13 others remained trapped inside an under-construction tunnel of the NHPC’s Teesta State-VI Hydroelectric Project in Sikkim’s Namchi district.
The project site is about 30 km south of Gangtok, the State capital.
A statement from the hydropower major said the incident occurred at 1:04 p.m. on July 20 inside the head race tunnel under construction at Samardung “due to sudden explosive release of suspected methane gas trapped/embedded in the rocks, resulting in the generation of dense smoke and toxic gases”.
A total of 25 personnel were trapped inside the tunnel, the NHPC said on Tuesday (July 21, 2026), citing information received from officials at the project site.
“Twelve people have died so far. Rescue operations for the others are underway,” Anupa Tamling, Namchi’s District Magistrate, told The Hindu.
The NHPC said the project team was working in close coordination with the district administration, the National Disaster Response Force, the State Disaster Response Force, local authorities, and other emergency agencies to support the rescue operations.
Rescue personnel conduct a rescue operation after about 25 workers are trapped inside an under-construction tunnel after a landslip blocked its entrance and triggered a suspected gas leak, in Namchi district. | Photo Credit: PTI
A total of 25 personnel were trapped inside the tunnel, the NHPC said on Tuesday (July 21, 2026), citing information received from officials at the project site.
“Twelve people have died so far. Rescue operations for the others are underway,” Anupa Tamling, Namchi’s District Magistrate, told The Hindu.
The NHPC said the project team was working in close coordination with the district administration, the National Disaster Response Force, the State Disaster Response Force, local authorities, and other emergency agencies to support the rescue operations.
Apart from top officials of the NHPC, a special rescue team from the Director General of Mines Safety has reached the site, closely coordinating with the rescue teams and local authorities.
“Our site engineering teams are working round-the-clock alongside the authorities to assist in stabilising the tunnel environment and ensuring rescue. A detailed investigation will be conducted to ascertain the cause of the incident,” the NHPC said.
On Tuesday morning, Prime Minister Narendra Modi called up Chief Minister Prem Singh Tamang to enquire about the situation and review the rescue operations.
“During the conversation, the Prime Minister expressed deep concern and compassion for the affected workers and their families. He assured the State government of all possible assistance from the Government of India to support the rescue efforts and provide relief to those impacted by the tragedy,” a Sikkim government statement said.
Later in the day, the Chief Minister inspected the project site with Governor Om Prakash Mathur. He announced that the State government would constitute a high-level inquiry committee to ascertain the cause of the incident.
“My heartfelt condolences go out to the families of the workers who have tragically lost their lives. In this moment of profound grief, the thoughts and prayers of the entire state are with the bereaved families,” Mr Tamang said, adding that the government would provide ex-gratia assistance to the families of the deceased workers.
Namchi’s Superintendent of Police, Sonam Dolma Bhutia, told journalists that a few bouts of rainfall since Monday affected the rescue operations to some extent. She also said seven of the dead workers have been identified so far. Three of them were from West Bengal, one each from Sikkim and Uttarakhand, and the rest from Assam
Published - July 21, 2026 10:43 am IST