Heavy destruction caused by the landslide led to the collapse of a newly-built bailey bridge at Sangkalang, leaving no link between Mangan, Dzongu and Chungthang. Several roads were blocked, houses damaged, electric poles swept away in the aftermath.

Mangan District Manager Hem Kumar Chettri said, "Three persons each died in Pakshep and Ambhithang villages."

Dzongu, Chungthang, Lachen and Lachung towns in Mangan district, which are known for their tourist spots of Gurudongmar Lake and Yunthang Valley have been cut off from the rest of the nation.

Chettri said that a relief camp has also been set up at Pakshep for those displaced. He also held a review meeting with other officials to access the situation following incessant downpour in and around Mangan since Wednesday night.

Chettri instructed the authorities to carry out rescue and relief operations and provide all possible assistance.

A request was made by the district administration to send a State Disaster Response Force (SDRF) team with ration to Mangan as mobile network services also remained affected in North Sikkim.

Notably, the bailey bridge was constructed after the large-scale social flood in Teesta river in October last year.

The stranded tourists were asked to stay where they were till an alternative road connectivity could be step for vehicle movements.

Sikkim Chief Minister Prem Singh Tamang asked the administration, police and officials of various departments to ensure swift assistance and response to the devastation. "Efforts are underway to provide every possible support to the victims and affected families, including recovery assistance, temporary settlement, and the provision of basic needs," Tamang said in a statement.

He further said that the state government stands firmly with the victims of the unfortunate incident and promises support to the bereaved families and all those affected and displaced by the landslides.

Tamang is currently in Arunachal Pradesh, where he went to attend the swearing-in ceremony of Pema Khandu. He will soon be back in Sikkim to personally oversee the rescue efforts.

The surging water in the Teesta river marooned the Melli stadium in Namchi district, officials said.

During the flash floods in the Himalayan state in October last year, nearly 50 persons lost their lives.

WHAT DOES IMD SAY?

The India Meteorological Department's (IMD) bulletin said that a cyclonic circulation lies over northeast Assam and neighbourhood and an east-west trough runs from northwest Bihar to Nagaland in lower tropospheric levels.

"Strong southwesterly/southerly winds are prevailing from Bay of Bengal to northeastern States in lower tropospheric levels," the bulletin said.

It said that widespread light to moderate rainfall with thunderstorm, lightning and gusty winds are likely over Arunachal Pradesh, Assam and Meghalaya, Nagaland, Manipur, Mizoram and Tripura and Sub-Himalayan West Bengal and Sikkim during the next seven days.

"Isolated heavy to very heavy rainfall very likely over Sub-Himalayan West Bengal and Sikkim during June 14-17," the weather office's bulletin said.

(With PTI inputs)