Downpour of the past 24 hours has triggered multiple landslides in parts of Sikkim, leaving one dead and injuring four others, besides damaging roads and disrupting traffic for hours together.

Rain also caused flash floods and waterlogging in a number of locations of the sub-Himalayan districts of Bengal, inconveniencing hundreds of people.

In Sikkim, the fatality occurred at Jholungay in Namchi district on Wednesday night when a huge boulder crashed on a staff bus of a Samardung-based pharmaceutical company ferrying workers to their homes at Lower Mamring. The distance between the two places is 5km.

“The incident took place around 11:30pm. A person died and four others got injured. One of them is critical and we shifted him to a hospital in Siliguri. The other three are admitted to the Central Referral Hospital in Gangtok,” said M. Bharani Kumar, the district collector of Namchi.

Kumar said that incessant rains led to landslides in Namchi district since Wednesday and three families from Dalep village had to be evacuated after a wall on the highway collapsed and damaged their houses on Wednesday.

In Mangan district, road connectivity between Chungthang and Lachen and Lachung snapped following landslides at many places.

“There's no road connectivity for many hours now. We are trying to open roads for movement of at least small vehicles. There have been multiple landslides and we are dealing with it with great difficulty,” said A.B. Karki, the district collector of Mangan.

The downpour has also affected areas of Alipurduar district in north Bengal. In Taribari area of Jaigaon, the town that shares borders with Bhutan, a flash flood washed away earth from under a number of houses, leaving them partially hanging.

Direct connectivity between Alipurduar and Falakata, 40km apart, snapped as many diversion roads were washed away by monsoon-fed streams Buri Torsha and Cha Torsha. People had to take longer detours.

Another diversion near Bhutanir Ghat has been washed away, snapping connectivity between Dhupguri and Falakata.

For 24 hours till 8.30am on Thursday, it rained over 200mm in Alipurduar. At least seven wards of Alipurduar town are waterlogged. People trudged through knee-deep and in some places waist-deep water on Thursday. A number of houses in low-lying areas have been inundated by the accumulated rainwater. The local civic body engaged water pumps to flush out the water to Kaljani river that skirts the town.

Rainfall led to waterlogging in parts of Jalpaiguri district and Siliguri sub-division.

It rained over 100mm in a number of places in the region while minimum rainfall was around 50mm.

Rainfall also affected a number of tea estates in the Dooars.

A bamboo bridge that links hamlets with Cooch Behar town damaged by the Torsha river on Thursday. Main Uddin Chisti

“Rainfall and rise in water levels of rivers and streams have washed away, patches of plantations have in some tea estates. If this situation persists and there is no sunshine, the industry will suffer,” said Chinmay Dhar, chairman of the Dooars branch of Tea Association of India.

Rainfall, however, is likely to continue for another three-four days, said Indian Meteorological Department sources. They said southwest monsoon is vigorous over sub-Himalayan Bengal and Sikkim and sounded an alert of heavy rainfall for the next 48 hours.

“Due to passage of the east-west oriented trough and strong moisture incursion from the Bay of Bengal, widespread moderate rainfall activity is very likely to continue,” said a weather expert.

“People should be on alert, especially in the hills as there can be landslides following heavy downpour. The state irrigation department has also flagged primary alerts in some rivers of the region,” said an administrative official.