Fourteen people have died and 102 others, including 22 army personnel, were missing after the cloudburst over Lhonak Lake in North Sikkim triggered a flash flood in the Teesta river basin, officials said on Thursday.

So far, 2,011 people have been rescued, while the calamity that happened on Wednesday affected 22,034 people, the Sikkim State Disaster Management Authority (SSDMA) said in its latest bulletin.

The state government has set up 26 relief camps in the four affected districts, it said.

A total of 1,025 people are taking shelter in the eight relief camps in Gangtok district, while the number of inmates at the 18 other relief camps was not available immediately.

The flash flood in the Teesta river, triggered by the cloudburst in Lhonak Lake in North Sikkim, caused accumulation of huge quantity of water, which turned towards Chungthang dam destroying the power infrastructure before moving downstream in spate, flooding towns and villages.

The flood destroyed 11 bridges in the state, with eight bridges getting washed away in Mangan district alone. Two bridges were destroyed in Namchi and one in Gangtok. Water pipelines, sewage lines and 277 houses, both kuchcha and concrete, have been destroyed in the four affected districts.

Chungthang town bore the maximum brunt of the flood with 80 per cent of it getting severely affected. The NH-10, considered the lifeline of the state, sustained extensive damage at several places.

Seven people died in Pakyong district, four people died in Mangan and three persons lost their lives in Gangtok, according to the SSDMA.

Among the 102 missing persons, 59 are from Pakyong, including the army personnel. Twenty-two are missing in Gangtok, 16 in Mangan and five people are missing in Namchi.

A total of 26 people sustained injuries, the SSDMA said.

Defence spokesperson Lt Col Mahendra Rawat said the Border Roads Organisation (BRO) was helping the state in the rescued operations in Chungthang and Mangan, where four critical bridges have been severely damaged.

"More than 200 people have been moved to safer areas by the BRO in spite of continuous heavy rainfall and extremely bad weather," he said.

"Search and rescue operations for the missing army personnel are still on," he added.

About 10,000 people have been affected by the calamity in the Mangan district, while 6,895 people were affected in Pakyong, 2,579 in Namchi and 2,570 people in Gangtok.