Family members of three persons from Bengal, who are among the 40 people trapped in Uttarakhand's Silkyara tunnel that collapsed on Sunday, are spending sleepless nights and hope that their loved ones would be rescued unharmed.

Soubhik Pakhira, 24, and Joydeb Pramanik, 18, both from two adjacent villages of Hooghly's Pursurah joined a private company last year and were posted at Silkyara tunnel construction site in Uttarkhand's Uttarkashi. The third trapped worker from Bengal, 30-year-old Manir Talukdar, is from Cooch Behar.

Pakhira, a diploma engineer, was home during Durga Puja and returned to his workplace earlier this month. Pramanik, who is a member of the survey team, has been at the project site for the past few months and was scheduled to visit his Hooghly home later this month.

A state government official said they were trying to get details about the nature of Talukdar's involvement in the project.

A source said 40 people, including the trio from Bengal, got trapped without food and water when the under-construction tunnel partially collapsed on Sunday morning.

The Narendra Modi government had approved the construction of the 4.521km two-lane Silkyara tunnel on the Yamunotri National Highway in 2018. The aim of the project is to connect Yamunotri, a popular pilgrimage for Hindus, with an all-weather road as the route gets blocked because of snowfall in winter.

The State Disaster Response Force (SDRF) and the National Disaster Response Force (NDRF) have been carrying out rescue operations since a portion of the tunnel collapsed.

A police officer in Hooghly said they contacted a government official in Uttarkashi who said that those trapped were safe and had been provided with liquid food and oxygen. Apart from the three from Bengal, most of the trapped workers are from Odisha, Uttar Pradesh, Bihar and Jharkhand.

"One of the seniors in the company where my son worked contacted me yesterday (Sunday) and informed me about the accident. He also said my son was among those trapped inside. He assured Soubhik is alive, but I can't be sure till I hear from him directly," Soubhik's mother Lakshmi Pakhira said.

A source said officials from Nabanna had already contacted their counterparts in Uttarakhand and were keeping themselves updated about the rescue operation.

"Officials in Uttarakhand have assured us that all three from our state are alive and unharmed till Monday evening. We are tracking all updates related to the rescue operation. However, we are keeping our fingers crossed till those trapped emerge safe from the tunnel," a senior state government official said, adding that Uttrakhand chief minister Pushkar Singh Dhami reached the spot on Monday to take stock of the situation.

Samirul Islam, chairperson of the West Bengal Migrant Workers' Welfare Board, said a team of Bengal government officials were in touch with their counterparts in Uttarakhand.

"We are always with the distressed families whose members are trapped in Uttarakhand. State government officials and local police have been in touch with them for time-to-time updates," said Islam, who is also a Trinamul Rajya Sabha member.