Nine dead and 15 trapped after tunnel collapse at India hydropower project

At least nine people have died and 15 others remained trapped after a tunnel collapsed at an under-construction hydroelectric project in India's remote northeast, officials said Tuesday.

The incident happened Monday in Sikkim, a Himalayan state, where workers were building a tunnel for a state-run hydropower project on the Teesta river.

Rajiv Roka, director of the Sikkim State Disaster Management Authority, said officials estimated that about 25 to 27 people were trapped. He said nine bodies had been recovered.

Officials said the collapse was likely triggered by a blast, but the cause had not been established. The region has had torrential monsoon rains in recent days. Roka said authorities were not sure what caused the blast because it happened deep in the tunnel, and said it was most probably natural.

Officials said toxic methane gas leaking from underground rock formations was hampering the rescue effort, with only teams carrying oxygen equipment able to enter. Roka said aggressive rescue operations were under way, but that the presence of gas was a major problem. He said a specialised team trained in mining accidents had been flown in to help rescuers.

Accidents on large infrastructure construction sites are common in India. Ecologists say excessive development projects have led to more disasters in fragile Himalayan areas.

In 2023, 41 workers were rescued after being trapped for 17 days under a collapsed Himalayan road tunnel in Uttarakhand state.