Several workers remained trapped inside an under-construction tunnel in Sikkim's Namchi district on Monday after a landslide blocked its entrance following a suspected methane gas explosion, officials said. Rescue operations involving multiple agencies continued late into the evening but were being hampered by hazardous gas, poor visibility and low oxygen levels inside the tunnel.

According to District Collector Anupa Tamling, the exact number of workers trapped inside the Samardung tunnel is still being verified and could change as rescue teams gather more information.

The incident occurred at the NHPC Teesta Stage-VI Hydroelectric Project's ADIT tunnel, being constructed by Patel Engineering. Officials said methane gas had reportedly accumulated around 1.5 kilometres inside the tunnel. An attempt to release the trapped gas is believed to have triggered an explosion, causing a landslide that sealed part of the tunnel and trapped the workers.

Some workers managed to escape immediately after the incident, but several others remained stranded deep inside.

RESCUE TEAMS STRUGGLE DUE TO GAS LEAK

The district administration received information about the incident around 3.40 pm, following which teams from the National Disaster Response Force (NDRF), State Disaster Response Force (SDRF), district police and Fire and Emergency Services rushed to the site.

An initial rescue attempt by the Rangpo Fire and Emergency Services had to be abandoned after rescuers experienced breathing difficulties because of low oxygen levels and gas inside the tunnel. Several personnel reportedly fell ill during the operation.

A subsequent attempt by NDRF teams also proved unsuccessful because of the dangerous conditions inside the tunnel.

To strengthen the operation, a specialised rescue team equipped with gas-protective equipment was dispatched from neighbouring West Bengal.

RESCUE OPERATION CHALLENGING

"It is estimated that 21 workers of contractor Patel Engineering and six of NHPC are stuck in the tunnel. Rescue operations are being carried out by teams of the National Disaster Response Force (NDRF), SDRF, district police and the Fire and Emergency Services. A specialised rescue team from neighbouring West Bengal has also joined the operation with gas-protective equipment for rescuers," District Collector Anupa Tamling said.

She added that the operation was becoming increasingly difficult because of methane gas exposure, the narrow tunnel and poor visibility.

Officials believe the gas may be naturally emanating from underground rock formations that were disturbed by the landslide, although the exact cause is yet to be confirmed.

Authorities have stationed ambulances near the project site while rescue teams wearing gas masks and other protective gear continue efforts to reach the trapped workers.

Senior district officials are monitoring the operation on the ground.

Tamling said the administration's immediate priority was to rescue all those trapped safely. A detailed investigation into the incident will be conducted once the rescue operation is completed.

As of the latest reports, no worker had been brought out of the tunnel, and rescue operations were continuing.

- Ends

Published On:

Jul 20, 2026 22:22 IST