(Rescue team. Photo by Union-bulletin)
In the northeastern Indian state of Sikkim, a gas explosion caused a section of an under-construction tunnel to collapse, killing at least 12 workers, according to officials.
Thirteen more people are reportedly stuck in the tunnel after Monday’s collapse, and rescue efforts are still working to find them.
The incident occurred approximately 1.5 kilometers (0.9 miles) inside the tunnel, according to the National Disaster Response Force (NDRF).
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).
According to NHPC, the accident occurred after a sudden burst of suspected methane gas trapped within the rocks led to an explosion that generated dense fumes and toxic gases.
In a separate statement, the Sikkim government said the accident was caused by methane gas combustion.
A government official explained that methane is a naturally occurring gas that can sometimes be trapped underground, and that tunnelling activity releasing it into a confined space, combined with a spark or other ignition source, can cause it to ignite or explode.
There were 27 people working in different sections inside the tunnel, two of whom managed to escape after the explosion, while 25 were trapped.
Superintendent of Police Sonam D Bhutia told online reporters on Wednesday morning that 12 bodies had been recovered so far out of the 25 trapped, with teams still working to locate the remaining 13 men.
Police said they had identified seven of the victims, one from Sikkim and others who were migrants from West Bengal, Uttarakhand and Assam states, adding that the cause of death would be confirmed following post-mortem examinations.
An NDRF officer, Mohsen Shahedi, told ANI news agency that the ongoing search-and-rescue operation was focused on a specific 200-metre zone where the remaining victims were likely to be located.
Chief Minister Prem Singh Tamang has set up a special investigation team in connection with the incident, telling reporters that a team of experts had been engaged to determine exactly what happened and how, with further action to be taken based on their findings.