Toxic gas kills 12 in Sikkim hydroelectric tunnel
A sudden release of suspected methane killed 12 workers and left 13 others trapped in an under-construction NHPC Teesta State-VI Hydroelectric Project tunnel in Sikkim’s Namchi district.
The project site is about 30 km south of Gangtok, the state capital.
A statement from the main hydropower plant said the incident occurred on July 20 at 13:04 inside the tunnel of the main plant under construction in Samardung “due to a sudden explosive release of suspected methane trapped/embedded in rocks, resulting in the generation of thick smoke and toxic gases”.
A total of 25 workers were trapped inside the tunnel, NHPC said on Tuesday (July 21, 2026), citing information received from officials at the project site.
“Twelve people have died so far. Rescue operations are underway for others,” Anupa Tamling, district magistrate of Namchi, told The Hindu.
The NHPC said the project team is working closely with the district administration, National Disaster Response Force, State Disaster Response Force, local authorities and other emergency agencies to support rescue operations.
Rescuers are carrying out a rescue operation after about 25 workers were trapped in a tunnel under construction after a landslide blocked its entrance and sparked a suspected gas leak in Namchi district. | Photo credit: PTI
A total of 25 workers were trapped inside the tunnel, NHPC said on Tuesday (July 21, 2026), citing information received from officials at the project site.
“Twelve people have died so far. Rescue operations are underway for others,” Anupa Tamling, district magistrate of Namchi, told The Hindu.
The NHPC said the project team is working closely with the district administration, National Disaster Response Force, State Disaster Response Force, local authorities and other emergency agencies to support rescue operations.
Apart from the NHPC top officials, a special rescue team of the Director General of Mines Safety also reached the spot and coordinated closely with the rescue teams and local authorities.
“Our engineering teams are working round-the-clock alongside the authorities to help stabilize the tunnel environment and ensure a rescue. A detailed investigation will be conducted to determine the cause of the incident,” NHPC said.
On Tuesday morning, Prime Minister Narendra Modi called Chief Minister Prem Singh Tamang to inquire about the situation and review the rescue operations.
“During the conversation, the Prime Minister expressed his deep concern and sympathy 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 assistance to those affected by the tragedy,” the Sikkim government said in a statement.
Later in the day, the Chief Minister inspected the project site with Governor Om Prakash Mathur. He announced that the state government would set up a high-level inquiry committee to find out the cause of the incident.
“My condolences to the families of the workers who tragically lost their lives. At this moment of deep sorrow, the thoughts and prayers of the entire state are with the bereaved families,” Tamang said, adding that the government would provide ex-gratia assistance to the families of the deceased workers.
Namchi Superintendent of Police Sonam Dolma Bhutia told reporters that several bouts of rainfall since Monday have affected rescue operations to some extent. She also said seven 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 – 21 Jul 2026 10:43 IST