3,000 people were marooned in Chapadanga, Premganj, Dakhin Changari area as the swollen river breached 100-metre embankment following release of 3,200 cusecs of water from Teesta barrage last night.
The Nagrakata-Kherkata link was also snapped as the bridge was washed away and the administration making arrangement to shift the stranded people.
Around 2,000 houses were submerged in the flood.
In Totopara hamlet, inhabited by an indigenous tribe, another 2,000 were marooned even as all communication links to Madarihat town was snapped.
The floods have jeopardised the panchayat poll preparations in the district, scheduled to be held on July 25.
Met office sources said there could be heavy rains in next 24 hours in the area.