Sikkim Tunnel Tragedy: Death Toll Rises to 12 as Massive Rescue Operation Continues at NHPC Teesta Stage VI Project

KalimNews, July 12, 2026, Gangtok : The tragic tunnel disaster at the under-construction 500 MW NHPC Teesta Stage VI Hydroelectric Project in Samardung, Jholungey, Namchi district of South Sikkim, has claimed 12 lives, according to the latest official update from the Namchi District Administration. Search and rescue teams remain on-site, working relentlessly under extremely hazardous conditions to locate and recover the remaining trapped workers.

The accident occurred on July 20 at about 1.04 p.m.inside the ADIT-3 (Head Race Tunnel) of the 500-megawatt Teesta Stage VI Hydroelectric Project. Initial reports indicate that a suspected methane gas explosion inside the tunnel triggered a collapse during excavation work, trapping workers deep underground. The blast filled the tunnel with toxic gases and debris, creating one of the most challenging rescue operations witnessed in the region in recent years.

Authorities stated that approximately 27 people were present in the tunnel when the incident occurred. Two workers managed to escape immediately after the explosion, while project workers and NHPC personnel remained trapped inside. Rescue efforts have since focused on reaching those caught beneath the collapsed section.

Officials believe methane gas, naturally trapped beneath underground rock formations, accumulated inside the tunnel before igniting and causing the devastating explosion. Geological experts have explained that the Teesta River basin lies within a highly fragile and seismically active Himalayan zone consisting of young rock formations, underground fractures, and gas pockets, making large-scale tunnelling operations particularly hazardous.

Dr. Devesh Walia, Professor of Geology at North-Eastern Hill University, observed that the region contains relatively young rock formations, including coal-bearing strata capable of trapping methane and other gases underground. According to him, the accumulation of these gases may have triggered the explosion.

Rescue operations have been severely complicated by dangerous concentrations of methane, carbon monoxide, and hydrogen sulphide inside the tunnel. Personnel from the National Disaster Response Force (NDRF) confirmed that the atmosphere remains highly toxic, forcing rescuers equipped with oxygen cylinders and protective gear to operate in short shifts of around 15 minutes at a time before withdrawing for safety.

Apart from poisonous gases, rescue teams are battling unstable ground, falling debris, extremely low oxygen levels, confined working spaces, and poor visibility. Several rescue personnel reportedly experienced dizziness and lost consciousness while attempting to reach the trapped workers, highlighting the extraordinary risks involved in the operation.

The rescue mission is being coordinated by the Namchi District Administration with support from multiple specialised agencies, including the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), Sikkim State Disaster Management Authority (SSDMA), Sikkim Police, Fire and Emergency Services, Mines Rescue Team from Asansol, Health Department personnel, medical teams from Rangpo Primary Health Centre, district authorities, and trained local volunteers. Additional specialised rescue teams from Pakyong, Siliguri, West Bengal, and other agencies continue working around the clock to recover those still trapped.

According to the latest official information, 12 bodies have been recovered from the collapsed tunnel. Authorities continue to search for the remaining workers, while identification of the deceased is being carried out carefully with assistance from fellow workers wherever necessary.

Among those whose identities have been confirmed are workers from West Bengal's Jalpaiguri district, Assam, Punjab, Uttarakhand's Dehradun, and Sikkim, reflecting the diverse workforce engaged in the hydropower project. One of the missing workers is reported to be Anish Mohan, a 43-year-old geologist from Kerala.

The incident has prompted the Sikkim Government to launch a Special Investigation Team (SIT) to determine the exact sequence of events leading to the disaster. Investigators will examine the suspected methane gas explosion, geological conditions, construction practices, and all other factors that may have contributed to the collapse.

Chief Minister Prem Singh Tamang personally visited the accident site to monitor rescue operations and directed all concerned departments to accelerate the mission while ensuring the safety of rescue personnel. He appealed to the public to avoid spreading unverified information and assured that every possible effort is being made to rescue those still trapped.

The Chief Minister announced financial assistance of ₹4 lakh for the next of kin of each deceased worker and ₹50,000 for every injured person. He stated that appropriate legal action would be initiated if the investigation establishes any negligence or lapses on the part of the executing agencies.

Expressing profound grief over the tragedy, the Chief Minister said the thoughts and prayers of the entire State are with the bereaved families and assured them that the Government would stand firmly beside them during this difficult time.

Prime Minister Narendra Modi spoke with Chief Minister Prem Singh Tamang to review the situation and expressed deep concern over the loss of lives. During the conversation, the Prime Minister assured the State Government of every possible assistance from the Government of India for rescue, relief, and rehabilitation efforts.

The Prime Minister also announced an ex gratia payment of ₹2 lakh from the Prime Minister's National Relief Fund (PMNRF) to the families of each deceased worker and ₹50,000 for those injured in the tragedy.

Union Home Minister Amit Shah also contacted the Chief Minister, reviewed the rescue efforts, and assured full support from the Union Government to assist the State in managing the ongoing emergency.

The Sikkim Legislative Assembly observed a two-minute silence at the beginning of its Budget Session to honour those who lost their lives in the disaster. Speaker Mingma Norbu Sherpa led the House in paying tribute to the deceased and extended condolences to the grieving families while wishing a speedy recovery to the injured.

As rescue operations continued, Chief Secretary Ravindra Telang chaired a high-level review meeting attended by senior officials from the State Government, district administration, rescue agencies, NHPC Limited, Patel Engineering Limited, West Bengal Administration, Sikkim Police, and the National Disaster Response Force.

The meeting reviewed the progress of search and rescue operations, strategies for safely accessing the collapsed tunnel, identification of the deceased, compensation procedures, and relief measures for affected families. The Chief Secretary instructed all agencies to ensure that every deceased worker is identified with dignity and that mortal remains are respectfully handed over to their families. He also stressed the importance of carefully managing the available oxygen supply to enable rescue teams to continue operations safely and efficiently.

District Collector Anupa Tamling stated that a clearer assessment of the situation would be possible only after rescue personnel gain complete access to the tunnel interior. Authorities have indicated that a detailed investigation into the causes of the collapse will proceed once rescue operations have been completed.

List of some of the persons who lost their lives in the incident

1. Bolo Oraon, Jalpaiguri, WB forwarded to Namchi District Hospital.

2. ⁠Gora Oraon, Jalpaiguri, WB forwarded to Namchi District Hospital.

3. ⁠Yasohal, Pathankot, Punjab, forwarded to Namchi District Hospital

4. ⁠Vikey Rawat, Deradhun, Uttarakhand

5. ⁠Bikesar Oraon, Jalpaiguri, West Bengal, forwarded to Namchi District Hospital

6. ⁠Babul Borodalai, Assam, forwarded to STNM Hospital.

7. Lakpa Dorjee Tamang, Katang, Namchi forwarded to Namchi District Hospital

8. ⁠Three unidentified bodies have been forwarded to District Hospital Singtam & STNM Hospital respectively.

9. Two more are in the process of identification.

According to NHPC, the accident occurred after a sudden burst of suspected methane gas trapped within underground rock formations triggered an explosion inside the under-construction tunnel. The blast rapidly filled the tunnel with dense fumes and toxic gases, significantly complicating rescue efforts.

Construction accidents remain a recurring concern across India, particularly in the Himalayan region, where fragile geology, seismic activity, heavy monsoon rainfall, landslides, and unpredictable underground conditions pose serious challenges to infrastructure projects. Experts note that tunnelling in these mountains requires continuous geological assessment and stringent safety protocols due to the presence of fractured rock formations and naturally occurring gases.

The Samardung tragedy has once again highlighted the immense engineering and safety challenges associated with executing major infrastructure projects in the Himalayan belt. Even as rescue teams continue their tireless efforts under life-threatening conditions, the State Government has reaffirmed that the situation remains its highest priority. Authorities have pledged full support to the affected families while continuing every possible effort to recover the remaining trapped workers and establish the exact cause of one of Sikkim's deadliest industrial disasters in recent years.