Consistent rainfall in sub-Himalayan Bengal, Sikkim and Bhutan over the past few days led to flash floods in vast areas of Jalpaiguri, Alipurduar and Cooch Behar.

The downpour made rivers that flow into these districts from Sikkim and Bhutan swell, causing erosion, floods and cave-ins.

IMD sources said the active southwest monsoon caused very heavy to extremely heavy rainfall in the past 24 hours (100mm to 200mm and more) in many places.

Armymen rescue villagers as the Kaljani river floods in Mechpara of Alipurduar on Thursday. Indian army

The regional Met office in Calcutta said it rained 290mm in Banarhat in Jalpaiguri, followed by Mangan in Sikkim (250mm), Buxadooar in Alipurduar (210mm), Nagrakata in Jalpaiguri (200mm), Murti in Jalpaiguri(190mm), Sankosh in Alipurduar (180mm) and Gajoldoba in Jalpaiguri (170). In Siliguri and Bagdogra, it rained 130mm and 150mm, respectively, in the past 24 hours.

In Alipurduar, Ruhinath Oraon, 65, drowned in the flooded Bangri river and Saidul Mistri, 45, who fell accidentally into the Torsha went missing.

The Goborjyoti river, which flows between Jaigaon and Alipurduar, washed away a part of its bridge's approach road, hitting traffic between Jaigaon and the rest of the district.

In Kalchini block, the Pana river flooded workers’ quarters of the Mechpara tea estate. DM Surendra Kumar Meena reached the garden along with civil defence, disaster management teams and army personnel. The Indian Air Force was contacted at Hasimara Air Force Station and an aerial survey done to locate stranded persons. Around 70 persons were rescued from Mechpara and shifted to safer places.

Hatinala, a stream flowing through Banarhat and Binnaguri of Jalpaiguri district, flooded different localities. Local streams inundated certain areas of Nagrakata block.

Rivers like the Teesta, the Jaldhaka and the Diana that flow through the district have flooded most banks. Nonai, a river flowing through Dhupguri block, damaged the approach road of a bridge.

The Torsha river floods its banks after a downpour in Phasirghat on the outskirts of Cooch Behar town on Thursday. Main Uddin Chisti

In Nagrakata and Matialli blocks, around 400 houses were inundated by flash floods. “We rescued around 300 families. All blocks are on alert,” said Moumita Godara Basu, the Jalpaiguri DM.

In Alipurduar, as the Kaljani river flooded Mechpara and washed away the only bridge that links the area with the highway, the administration sought the help of the Indian army. Troops of the Kripan division of the Trishakti Corps evacuated 72 villagers, including 24 children. Army personnel left only after confirming no one was stranded.

In Cooch Behar, the Torsha river that descends from Bhutan flooded several areas.

Rainfall led to landslides in Sikkim, particularly in Mangan district.

In Bhutan, rain led to landslides and blocked roads in at least 27 spots, said sources. Bhutan's National Centre for Hydrology and Meteorology warned of intense rainfall. Phuentsholing sources said the city's multi-level carpark could get flooded.