Sikkim: 10 dead and 17 missing after hydroelectric tunnel explosion in India

Herz — World Desk · 21 July 2026 at 15:46 · 30s summary · 2 min read

What we know

At least 10 people have died and 17 others remain missing after a tunnel collapsed during construction in the state of Sikkim, northeastern India, on July 21, 2026, according to Al Jazeera. The death toll was confirmed by Sonam Dolma, the local police chief.

The accident occurred at Samardung, near the border with Bhutan and Tibet. The tunnel is part of a 500-megawatt hydroelectric project on the Teesta River, operated by the National Hydroelectric Power Corporation (NHPC), a state-owned hydroelectric utility in India.

The NHPC attributed the explosion to a sudden release of gas—likely methane—trapped in the tunnel's rock. Survivors described a loud detonation followed by a collapse of debris.

Rescue workers trapped too

Six NHPC officials who had entered the tunnel to assist with rescue efforts became trapped themselves, worsening the situation.

Teams from the National Disaster Response Force (NDRF), India's national disaster response agency, detected three types of toxic gases in the tunnel: methane, carbon monoxide, and hydrogen sulfide. Specialized respiratory equipment is required to progress inside the tunnel.

Context: A geologically risky zone

Experts cited by the Associated Press indicate that the Teesta River basin is a seismically active zone. The rock formations there are young and fragile, crisscrossed by fractures and underground pockets capable of accumulating gases and causing explosions.

Notable precedent in 2023

In 2023, 41 workers were trapped for 17 days in a collapsed tunnel in the state of Uttarakhand, in northern India. All were eventually rescued, illustrating the recurring nature of such accidents in the Himalayan region.

What remains uncertain

It is not established how many of the 17 missing people are still alive. The nature of the gas involved remains qualified as "likely" methane by the NHPC, without definitive confirmation. It is also unclear whether the six NHPC officials trapped are included among the 17 missing or in addition to that number.