A methane gas explosion at a hydropower project tunnel in Sikkim, India, has left 25 workers dead, with the final body recoveries completing on July 23, 2026, according to state authorities. The blast occurred at approximately 1:00 p.m. on Monday, July 20, 2026, at the Teesta Hydroelectric Project in Namchi district, roughly 40 kilometers (25 miles) south of state capital Gangtok.
The National Hydroelectric Power Corporation (NHPC), which oversees the 500-megawatt project, announced it would pay 500,000 Indian rupees ($5,178) in ex-gratia relief to families of those killed. Among the victims were two NHPC officers, including Anish Mohan, a senior geologist. Many of the dead were migrant laborers from West Bengal, Jharkhand, Bihar, and Assam.
One source reported that the death toll had reached 25 as rescue operations wound down on July 23, revised up from an earlier count of 22 while crews were still searching for remaining victims.
Toxic Gases and Underground Hazards
NHPC attributed the catastrophe to a “sudden burst of suspected methane gas present inside the rocks, which led to an explosion generating dense fumes and toxic gases,” NHPC said. Dense smoke filled the passage immediately after the explosion, while rescue efforts were hampered by mud and water buildup inside the tunnel in addition to the toxic gases.
Surviving workers claimed they had complained about unusual underground conditions for nearly two months prior to the explosion.
Recovery teams worked for four days, carrying oxygen cylinders into the passage and battling hazardous fumes throughout the operation. An official in Namchi district confirmed on July 23, 2026, that crews extracted the final three victims during the afternoon hours. Of those trapped, 19 worked for Patel Engineering Limited, a contractor on the hydroelectric project.
After all victims were recovered, crews carried out a concluding examination of the affected area. “Tragically, all 25 individuals lost their lives, and their bodies were recovered during the course of the operation,” authorities said.
Investigation Underway
A high-level committee has been formed by the Sikkim state government to probe what happened and produce guidelines aimed at stopping future tragedies of this kind. Initial reports identified a leak of flammable gas as the probable cause, but authorities warned that investigators have yet to finalize their determination and are awaiting specialist review. NHPC disputed media reports suggesting a landslide set off by the blast had caused the tunnel to collapse.
The basin of the Teesta River, where construction is underway, lies within a seismically volatile area marked by geologically recent, fractured bedrock capable of trapping prehistoric gas deposits. Experts say that earthquake risk and erratic subterranean environments increase hazards during tunnel excavation throughout this Himalayan corridor. The facility is situated close to Samardung village in Namchi district.
India’s Infrastructure Push and Safety Concerns
This tragedy marks the latest in a series of deadly incidents tied to India’s aggressive infrastructure expansion, especially across its northern and northeastern mountain zones. Such construction disasters recur regularly amid this rapid development, as urgent timelines clash with unstable terrain, variable adherence to safety protocols, harsh climate conditions, and the brutal challenges of boring through geologically ancient mountains.
In February 2026, a coal mine blast in Meghalaya state claimed roughly 30 lives. Earlier, in 2023, a collapsing tunnel in Uttarakhand state in the north trapped 41 laborers below ground for over two weeks until all were rescued alive.
NHPC commissioned the Teesta Hydroelectric Project to advance India’s push to harness electricity from its Himalayan waterways. The Teesta River, fed by Sikkim’s lofty glaciers and flowing into West Bengal’s lowlands, has been targeted for years as a renewable power source. Yet the region’s geologic immaturity — which yields powerful water flows due to newly formed stone, precipitous slopes, and shifting tectonic plates — simultaneously renders it among the world’s most dangerous settings for subsurface excavation.
The investigative panel will likely scrutinize both the immediate ignition source for the methane that Monday afternoon and whether broader institutional lapses left laborers exposed to danger with inadequate protections. For relatives gathered outside the tunnel mouth in Samardung village, the conclusion of recovery efforts offered no comfort — merely final proof of the tragedy they had dreaded since the explosion.