The Teesta river, which swelled because of a cloudburst in north Sikkim on Tuesday night, flooded a number of areas on both its banks downstream in north Bengal's Jalpaiguri and Cooch Behar districts.

On Wednesday morning, the state irrigation department rang a red (secondary) alert as the river, gushing downstream, reached the danger level at Gajoldoba in Jalpaiguri, where there is a barrage on the river.

“Around 10am, 8,252 cumecs of water was released from the barrage. Added to it, every hour, 6,000 to 7,000 cumecs of water were released till afternoon to handle the situation. In recent years, there is hardly any instance when water in such high volume has been released from the barrage to downstream,” said an official of the irrigation department.

The Teesra river flooded a number of low-lying areas in Kranti, Rajganj and Mainaguri blocks of Jalpaiguri district.

“The damage could be controlled as since early Wednesday morning, people from these areas were asked to vacate their houses and shift to safer places,” said a source in Jalpaiguri district administration.

In Mekhliganj, the subdivision in Cooch Behar from where Teesta enters Bangladesh, the administration along with the BSF started rescue operations. The BSF reached Singhpara, an islet in the Teesta barely 300km from the Indi-Bangladesh border, and rescued 183 residents.

“Suddenly, water levels started to rise. We were worried but found the BSF personnel reaching our place in boats. They brought us to the riverbank. We are relieved but have no idea as to whether the river has flooded our hutments,” said Nurbanu Begum, a resident of Singhpara.

Residents near the river on both banks were moved to higher places in Mekhliganj. The administration made public announcements, asking them to be alert.

In Jalpaiguri, the police regulated traffic on the bridge over the Teesta on NH27, as the water level rose.

“The water level started receding in the evening. But what concerns us is the forecast of more rainfall in the region,” said an official of the irrigation department.

He added that on Thursday, the state irrigation minister will reach the region for a meeting in Gajoldoba and visit some affected areas

Weather experts said the southwest monsoon was active over the Gangetic Bengal, Sikkim and sub-Himalayan Bengal.

“There is a forecast of heavy to very heavy rainfall (70mm to 200mm) during the next couple of days in Jalpaiguri, Kalimpong, Sikkim, and Birbhum and Murshidabad. A red alert on rainfall has been rung across Sikkim,” said a source in the regional Met office, Calcutta.