Workers Trapped After Blast at Sikkim Hydropower Tunnel

Rescue teams are battling hazardous gas, low oxygen, and blocked passages at the Samardung tunnel in Sikkim. The incident occurred at the under-construction Teesta Stage VI Hydroelectric Project in Namchi district.
 

Hazardous Gas Slows Rescue Teams in Namchi

A major Samardung tunnel rescue operation continued in Sikkim’s Namchi district on Tuesday, July 21, 2026, after a suspected methane gas incident and landslide blocked an under-construction tunnel and trapped workers deep inside.

The tunnel is part of the Teesta Stage VI Hydroelectric Project near Samardung and Mamring. Rescue teams have encountered hazardous gas, low oxygen levels, poor visibility, and restricted movement inside the narrow underground passage.

Early reports said seven workers had died and several others remained trapped. However, the casualty figures changed repeatedly as the operation progressed, with later media reports placing the toll between eight and ten. Officials said the number of people inside the tunnel also remained provisional while teams worked to reach the affected section.

Samardung Tunnel Rescue Operation Faces Hazardous Conditions

Personnel from the National Disaster Response Force, State Disaster Response Force, Sikkim Police, Fire and Emergency Services and the district administration have been deployed at the site.

Initial rescue attempts were interrupted after emergency personnel experienced breathing difficulties, dizziness and other symptoms linked to the suspected presence of methane gas and reduced oxygen levels.

Specialised personnel carrying gas-protective equipment were subsequently brought in to strengthen the operation. Additional NDRF teams from Pakyong and Siliguri were also mobilised.

The challenging atmosphere has prevented rescue teams from moving quickly through the tunnel. Officials said safety checks were necessary before personnel could advance further into the affected area.

What Happened at the Teesta Stage VI Tunnel?

The incident was reported on Monday afternoon inside the tunnel being constructed for the Teesta Stage VI Hydroelectric Project.

According to preliminary accounts, workers heard a loud blast-like sound before a landslide or structural blockage sealed part of the passage. Methane gas is suspected to have accumulated inside the tunnel, although authorities had not conclusively established the sequence of events.

One account suggested that gas had collected approximately 1.5 kilometres inside the tunnel and that an explosion may have followed an effort to release it. A detailed technical investigation will be needed to determine whether the gas incident triggered the landslide or occurred after the passage was blocked.

Worker Count Remains Uncertain

Conflicting reports emerged regarding the number of workers trapped or rescued. Some reports referred to 25 workers, while other accounts estimated that around 27 people may have been inside, including employees and personnel who entered during early rescue attempts.

Namchi District Collector Anupa Tamling said the figures were provisional because rescuers had not initially reached the exact location where workers were believed to be trapped. Authorities therefore continued verifying attendance records and information supplied by workers who escaped.

Because the rescue remains an evolving operation, official confirmation from the district administration should be treated as the final authority on casualties and evacuations.

Prime Minister Reviews Rescue Efforts

Prime Minister Narendra Modi spoke with Sikkim Chief Minister Prem Singh Tamang to enquire about the incident and the continuing rescue mission. The Chief Minister said the state was coordinating with emergency agencies and providing support to those affected.

The immediate focus remains on reaching the workers safely while protecting rescue personnel from toxic gas and unstable tunnel conditions. Medical teams and emergency vehicles have been positioned near the site to assist anyone brought out of the tunnel.

The incident is also expected to prompt questions about ventilation, gas monitoring, emergency exits, and worker-safety procedures at underground hydropower construction sites.