Bad weather hampered efforts to reach the worst-hit areas of the Sikkim flash floods on Friday, forcing army and national disaster response force (NDRF) personnel to begin trekking and even taking boats to reach the devastated hillside villages, according to people aware of the matter.

Read here: Residents pick up pieces after Sikkim floods leave behind trail of destruction

The known number of casualties rose to 27 and the number of missing increased to 143, officials said, as fears strengthened that true scale of the loss, in material and life, may be worse than currently estimated.

The confirmed fatalities were all of bodies found floating in the Teesta river in Bengal’s Cooch Behar, Jalpaiguri and Darjeeling districts – hundreds of kilometres from Mangan in North Sikkim, which bore the brunt of Wednesday’s flash flooding.

“The bodies of 27 victims have been found in West Bengal districts so far. Of them, at least five are army personnel,” Shama Parveen, district magistrate of Jalpaiguri, told HT.

Around 1.30am on Wednesday, a glacial lake outburst flood (GLOF) triggered by torrential rain slammed into the Chungthang dam, cleaving the structure and barrelling downhill where it left villages and towns buried under silt and debris.

Many bridges have been destroyed, and power lines are down, hampering communication as well as access to an area where thousands are believed to be trapped.

Sikkim chief minister Prem Singh Tamang told the media that damages may run up to thousands of crores of rupees but exact details will be assessed only after a committee is formed for a survey.

Tamang, who visited affected areas at Rangpo in Pakyong district, said 25,000 people have been affected and 3,500 rescued from cut-off areas.

“The state is trying to rescue tourists stranded at places such as Lachen and Lachung in north Sikkim. Helicopters are not being able to fly due to inclement weather. NDRF teams are waiting at Bagdogra airport (in West Bengal) to fly to North Sikkim,” said Tamang.

The CM said he had spoken to Prime Minister Narendra Modi, Union home minister Amit Shah, President Droupadi Murmu, and several Union ministers.

“They assured me that all necessary assistance will be provided,” he said.

Shah approved the release of ₹44.8 crore as an advance amount from the Central share of the State Disaster Response Fund (SDRF) to Sikkim. The Union home ministry formed an Inter-Ministerial Central Team (IMCT) that will visit the affected areas to assess the damage, the Centre said in a statement.

Among the those feared dead are 22 army personnel, who were swept away when flood waters hit the Bardang army camp area. One of the 23 army personnel who were initially reported as missing was later rescued.

The waters also swept away vehicles and crates of ammunition and mortars, prompting authorities to sound a warning that citizens should not touch anything found along the banks of the Teesta. Despite the warning, Sahinur Alam, a seven-year-old boy, died and five men were injured in an explosion in Bengal’s Jalpaiguri district on Thursday evening when they tried to disassemble a mortar found on the river bank.

Of the 22 civilians whose bodies were found, 15 are male and six are female, reported PTI, adding that the gender of one person could not be ascertained because the body was badly damaged.

Sikkim State Disaster Management Authority (SSDMA) said in a bulletin on Friday that 7,644 people displaced by the floods have been sheltered at 26 relief camps in four affected districts.

Continuous rainfall and bad visibility stopped the Sikkim administration from using choppers in rescue operations.

While an Mi-17 chopper couldn’t take off, two Mi-17 choppers flew from Bagdogra but had to return as there were low clouds in the hills, restricting visibility. Later a Chetak helicopter was also pressed into action but it too had to return. Two companies of NDRF personnel were waiting in Bagdogra airport near Siliguri town till Friday evening.

Read here: Sikkim CM Prem Singh Tamang questions quality of hydel dam destroyed in flood

“At least 13 persons, all of whom are employees of the Teesta hydel power project are feared trapped in a tunnel in Chunthang. An NDRF team was supposed to look for the survivors. Since the team did not arrive, we are sending a police team. The area is totally inaccessible and the police team will have to trek for five hours to reach the spot,” said an Sikkim police official associated with the rescue mission.

Of the bodies recovered till Friday, one was found by the border guarding agencies in Bangladesh, said a BSF official in north Bengal.

“Since NH-10, Sikkim’s lifeline, has been damaged badly, small and light vehicles from Siliguri may reach Gangtok via Gorubathan, Lava, Munsong and Rangpo, while those heading towards southwest districts of Sikkim may move via Darjeeling, Singla and Jorethang,” a senior Sikkim police official said.