Fifteen Indian workers were feared trapped on Tuesday after a blast caused by a suspected gas leak in a tunnel at a hydroelectric project in the rugged state of Sikkim killed ten, authorities said.
A sudden burst of gas, suspected to be methane trapped or embedded in the tunnel's rocks, caused an explosion that sent dense fumes and toxic gas, NHPC said in a statement.
Monday's incident took place at state-owned National Hydroelectric Power Corp Ltd's project on the Teesta river in the northeastern state's village of Samardung, district official Subash Ghimirey told Reuters.
Survival chances are 'slim,' says Indian official
Survival chances for the trapped workers were slim, state disaster management official Rajiv Roka said, as rescuers had to battle the fumes, making their task difficult.
At least 25 project workers and officials were trapped in the tunnel, NHPC said, a tally that includes the 10 bodies retrieved.
Photographs on the state government's Facebook page showed rescuers wearing orange hazard suits unloading oxygen cylinders, ropes and other emergency equipment from a vehicle.