Over 1,000 members of different rescue teams have not yet managed to reach a tunnel at Tapovan village in Uttarakhand where 25 to 35 workers are feared trapped following Sunday’s avalanche, as the toll climbed to 31 on Tuesday.

Personnel from the Indian Army, Indo-Tibetan Border Police and the national and state disaster forces are involved in the search and rescue operation.

The emergency control room opened at chief minister Trivendra Singh Rawat’s secretariat said on Tuesday that besides the 31 people whose bodies had been recovered, 175 people are missing. They include those feared trapped in the tunnel, whose numbers have been estimated based on information from companies contracted for the work. Of the 31 found dead, two are yet to be identified.

The dead include two police constables on duty at the Niti Valley in Chamoli district.

Divya Dutt, a loader operator involved in the construction of tunnels of the Rishi Ganga and Tapovan hydel power projects who is now assisting the rescue teams, told reporters on Tuesday evening: “There is one main tunnel, two smaller linear tunnels and one semi-circular tunnel. We have begun entering the matrix from the tunnel that begins on the banks of the Rishi Ganga river.

“We have been able to clear debris from a stretch of about 90 metres into the tunnel. We need to clear debris strewn over another 90 metres or so before reaching the area where the tunnel branches out into other tunnels. The workers could be trapped somewhere inside the nebulous structures.”

“The operation is scary. The condition of the tunnel is horrible. All we are thinking at this moment is whether we would be able to rescue some of the people who may be trapped somewhere inside the tunnels,” he added.

It had been initially thought that a glacial outburst on the Nanda Devi mountain had brought down with it water, mud, gravel and rocks. However, the Indian Institute of Remote Sensing, a wing of the Indian Space Research Organisation in Dehradun, said on Monday evening that a landslide at an altitude of 5,600 metres had triggered a snow avalanche in an area of 14sqkm and caused a flash flood in the downstream of the Rishi Ganga.

Villagers of Raini and Tapovan, the worst-affected villages, are yet to recover from the shock of Sunday’s calamity.

Amrita Devi, 72, who had been working in an agricultural field at Raini near the Tapovan dam that was destroyed, was washed away and is yet to be traced.

“I was a little distance away when a mass of ice and also water came hurtling down the Nanda Devi. Within a few seconds, the water level in the Dhauli Ganga river rose

and everything was washed away in front of my eyes, including my grandmother. Everything happened within a few seconds,” said Amrita’s grandson Gaurav Singh.

Devendra Singh of the same village told reporters that he and his younger brother Sanjay Singh were on the banks of the Rishi Ganga with their goats when the avalanche struck.

“As the level of the river suddenly rose, I managed to run to safety but my brother couldn’t. He and all the houses and towers were swept away in no time,” Devendra said.

Bhawan Singh, the panchayat chief of Raini, said: “Yashpal Singh, a resident of my village, had gone near the river with his 22 goats. Madhi Devi and Ranjeet Singh were also there to collect fodder for cattle. They are all missing, as are Kuldeep Singh and his son Ashutosh.”

“The rescue teams have confirmed that constable Balbeer Singh and Manoj Chaudhary, who were on duty, are dead and their bodies have been recovered from the riverbed,” said the village chief, adding that some people from Tapovan, Jaunsar Bawar, Dadoli, Sahiya, Fateu and Jagju villages who were near the Rishi Ganga river were also missing.