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 10, authorities said.Monday’s incident took place at state-owned National Hydroelectric Power Corp’s (NHPC) project on the Teesta river in the northeastern state’s ⁠village of Samardung, district official Subash Ghimirey said.A sudden burst of gas suspected to be methane trapped or embedded in rocks ‌in the tunnel caused an explosion that sent out ⁠dense ⁠fumes and toxic gas, NHPC said in a statement.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.