Twelve workers were killed and 13 others remain trapped after a tunnel collapse at a hydroelectric project in India’s Sikkim state. The disaster, triggered by a methane gas explosion, occurred Monday while crews were working on the National Hydroelectric Power Corporation’s infrastructure project near the Teesta River.
Methane Explosion at the Teesta River Project
The incident took place approximately 1.5 kilometers (0.9 miles) inside an under-construction tunnel designed to divert water from the Teesta River to a hydropower plant’s turbines. According to the state-owned National Hydroelectric Power Corporation (NHPC), the collapse followed a sudden release of gas trapped within the rock formations. The company stated the event occurred after [a] sudden burst of suspected methane gas trapped/embedded inside the rocks which led to [an] explosion generating dense fumes and toxic gases.
Government officials in Sikkim confirmed the primary cause of the disaster was methane gas combustion.
Methane is a naturally occurring gas that can sometimes be trapped underground; if tunneling releases it into a confined space and it comes into contact with a spark or another ignition source, it can ignite or explode, according to a government official. The project site is located in the village of Samardung, according to district official Subash Ghimirey.
Search and Rescue Operations
There were 27 people working in different sections inside the tunnel when the explosion occurred on Monday. Two individuals managed to escape, leaving 25 others trapped behind the debris and toxic fumes. While NHPC initially reported at least 25 project workers and officials were trapped, the tally includes the bodies retrieved. By Wednesday morning, authorities had confirmed the recovery of 12 bodies.
Superintendent of Police Sonam D Bhutia told the BBC on Wednesday morning, Of the 25 people who were trapped, we have recovered 12 bodies so far, and teams are working to locate the 13 other men.
Rescuers are currently focusing their efforts on a specific 200-meter zone where the remaining workers are believed to be located. National Disaster Response Force (NDRF) officer Mohsen Shahedi noted that the operation is complicated by the presence of dense fumes, making the task difficult for rescue teams. State disaster management official Rajiv Roka stated that survival chances for the trapped workers were slim due to the hazardous environment. Photographs on the state government’s Facebook page showed rescuers wearing orange hazard suits unloading oxygen cylinders, ropes, and other emergency equipment from a vehicle to aid the search.
For more on this story, see Sikkim Tunnel Collapse: 12 Dead and 13 Missing After Gas Explosion.
Victim Identification and Investigation
Police have identified seven of the 12 deceased workers. The victims include one person from Sikkim, while others are migrants from the states of West Bengal, Uttarakhand, and Assam. Official causes of death will be ascertained after a post-mortem examination is completed.
In response to the tragedy, Sikkim Chief Minister Prem Singh Tamang has established a special investigation team to determine the circumstances of the explosion. Tamang stated, We have engaged a team of experts to find out what exactly happened and how. We will take action on the basis of the findings.
Related Incident in China
Separately, a tunnel under construction collapsed on Tuesday at a hydropower station in Suichuan County, located in east China’s Jiangxi province, resulting in four deaths. Local publicity authorities stated the accident occurred around 2:00 a.m. Three people died at the scene, while a fourth victim died after being transported to a hospital. Safety inspectors are currently investigating the cause of the collapse at the station, which is being built by Jiangxi Water and Hydropower Construction.
Operational Context and Safety Oversight
The Sikkim tunnel project is an infrastructure undertaking in the Himalayan state, overseen by the NHPC to utilize the flow of the Teesta River for energy production. The nature of the accident—a gas-related explosion in a deep-rock tunnel—highlights the geological risks associated with tunneling projects in rugged terrain.
While investigations into the specific ignition source continue, the focus remains on the immediate recovery efforts. The site remains under emergency management, with crews utilizing specialized gear to navigate the atmosphere inside the tunnel. The government has yet to announce a formal report on the safety protocols in place at the time of the blast.
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