Between 6am and 6.30am on Friday, a team of 60 rescuers from the National Disaster Response Force (NDRF) will be on tenterhooks. They will be travelling to remote Chungthang in North Sikkim. The challenge in front of them is daunting – a dozen-off people feared trapped in tunnels for 48 hours without food, water or any possible exit. Nobody knows if the tunnels are inundated or not. Nobody knows if the 12-14 people are dead or alive.

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With the task at hand largely unknown, the rescue team will comprise land rescuers and scuba divers. They will be armed with hammers, water guns, rock cutters, satellite phones, generator sets and lifesaving medical equipment.

Power lines snapped, cell towers wrecked, bridges destroyed and roads washed away – Wednesday’s flash floods have cut Chungthang town off from the rest of Sikkim. The connectivity blackout has meant that there is no information on the people trapped. All that’s known so far is that they work with a state government firm that manages the Teesta -III dam. The tunnels are all within the Teesta-III dam compound, which was destroyed during Thursday’s flash floods.

The Sikkim government on Wednesday acted on information from local authorities and informed the Centre, which ordered that an NDRF team be sent to the tunnels.

For now, the team is hopeful.

“Our teams are ready and we hope they are all alive. By the time we reach, it will be more than 48 hours since the incident, But we are positive that they are alive,” said an NDRF official aware of the operation.

Workers at the dam used the tunnels, each no more than 200m long, to criss-cross the reservoir.

The rescue operation will, in some ways, be reminiscent of the 2018 Thailand rescue, where divers rescued 13 people – 12 boys and one man – who were trapped in a flooded cave for nearly six days.

The success of that mission, unlikely as it was, kept the NDRF team going, as they waited in Bagdogra in West Bengal on Thursday evening, counting every minute before they are airlifted to Chungthang.

But another unknown stared at them as they waited – the weather.

The India Meteorological Department (IMD) on Thursday said showers will spare rain-wrecked north Sikkim on Friday. But the mission could be disrupted if the conditions are unconducive.

“Even though the rain subsided today (Thursday), the weather was still rough and it was not possible to airlift the team. IMD has predicted decent weather for Friday. So at first light, our rescuers will board the chopper and head off for a helipad in Chungtang,” said the official quoted above.

“The local administration has confirmed that the helipad has not been affected so landing there is not a problem.”

Before the rescuers board the IAF chopper, another helicopter will head out on a sortie to ensure the weather is safe for the mission, said officials.

While rescuers involved in operations across the flood-ravaged hill state on Wednesday managed to reach Singtam and Rangpo, the scale of devastation meant they were unable to head towards Chungthang. Rescuers said they are prepared for a bunch of scenarios.

They will be armed with equipment that can slice through rock and boulders that may have trapped the people in the tunnels. They will also pack sensors that can detect life if a person is trapped under debris. NDRF teams used similar sensors during operations to rescue people trapped in the Turkey-Syria earthquake this February. During that rescue, the force rescued two girls trapped in debris for 72 hours.

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The satellite phones will help the rescue teams make urgent calls to nearby camps if required. And if the people are rescued on time, they can be airlifted to the medical camps in nearby regions run by the Indo-Tibetan Police Force (ITBP) and the Army. Another scenario the rescuers anticipate is survivors who may have crossed the tunnels and headed to the riverbanks.“This will involve negotiating the deep water near the tunnels,” the first official added.

The 60-strong team that boards the chopper on Friday morning stare at a great unknown. Their ability to save lives may depend on the conditions, and on their ability to overcome a series of stiff challenges.