Tunnel collapse in India kills 25 workers
Bipin PokhrelTwenty-five men working in an under-construction tunnel in India's north-eastern Sikkim state were killed after a portion of it collapsed following a gas explosion, officials said.
The incident took place on Monday afternoon, and the rescue operation concluded on Thursday night, after the last of the 25 trapped bodies was recovered.
The National Disaster Response Force said the incident happened about 1.5km (0.9 miles) inside the tunnel.
The under-construction tunnel, designed to carry water from the nearby Teesta River to a hydropower plant's turbines, is part of a larger project in the Himalayan state being developed by the state-owned National Hydroelectric Power Corporation (NHPC).
"The rescue operation at the under-construction Head Race Tunnel (HRT) of NHPC's Teesta Stage-VI Hydroelectric Project in Sikkim has been concluded with the recovery of bodies of all the 25 personnel trapped inside the tunnel," NHPC said in a statement.
The incident happened "after sudden burst of suspected methane gas trapped/embedded inside the rocks which led to [an] explosion generating dense fumes and toxic gases," it said.
In a separate statement, the Sikkim government said the accident was caused by "methane gas combustion".
Methane is a naturally occurring gas that can sometimes be trapped underground. If tunnelling releases it into a confined space and it comes into contact with a spark or another ignition source, it can ignite or explode, a government official said.
There were 27 people working in different sections inside the tunnel - of which two managed to escape after the explosion, and 25 were trapped.
Several of the victims are migrants from other states that include West Bengal, Uttarakhand and Assam, Superintendent of Police Sonam D Bhutia told the BBC.
Officials say their cause of death will be ascertained after a post-mortem examination.
Chief Minister Prem Singh Tamang has set up a special investigation team in connection with the incident. "We have engaged a team of experts to find out what exactly happened and how. We will take action on the basis of the findings," Tamang told reporters.