Three days of incessant rains have triggered flood in parts of Chattorgram, Feni, Sylhet, Ranagmati, Habiganj, and Moulvibazar districts, reports UNB.
Thousands of people have been already been affected by the flood.
In Chattogram, severe flooding was reported on Wednesday from Hathazari, Raozan and Fatikchhari.
In Hathazari, regional roads, fish enclosures, houses and business establishments were submerged by the rainwater.
Hathazari-Rangamati, Hathazari-Khagrachhari and Hathazari-Oxygen roads also got inundated, causing immense sufferings to commuters.
Hathazari Upazila Nirbahi Officer (UNO) Akterunnesa Sheuli said the local administration has taken all-out preparations to tackle any kind of natural disaster.
The inhabitants of low-lying areas have been asked to take shelter in local educational institutions, she said.
In Raozan, heavy rains flooded many low-lying areas in the upazila, leaving one lakh people in six unions--Haldia, Dabua, Chikdair, Ghahira, Noajishpur, Purbagujra and Raozan-- marooned.
People were seen wading through knee-deep water on Chattogram-Rangamati road on Tuesday. Besides, traffic remained suspended on the road due to flood.
Shamim Hossain, UNO of Raozan upazila, said onrush of water from hills and persistent rains for the last three days submerged six unions of the upazila.
A total of 24 shelter centres have been opened in the area, he added.
Besides, the leave of all the employees and staff of the local administration were cancelled and all of them asked to remain in their workplaces round the clock, the UNO added.
In Fatikchhari upazila, 50 villages were inundated by floodwater, rendering three lakh people marooned.
Khurshid Alam, Gauge Station officer of Water Development Board in Narayanhat, said the water in the Halda River has been flowing 5.90 centimeter above the water level till 6 pm on Tuesday.
In Rangamati, 14 villages in Baghaichhari upazila of the district were submerged due to rains and onrush of water from hills for the last three days, leaving 60,000 people marooned.
Besides, the water in the Kaptai Lake was flowing over the danger level inundating the low-lying areas of the upazila, including Longdu, Jurachhari, Barkal, Bilaichhari and Naniarcharareas.
AKM Mamunur Rashid, deputy commissioner of Rangamati, said several villages were flooded as the water in the Kachalong River rises following the rain.
Several shelters centres were opened for flood-affected people and around 10 tonnes of rice was distributed among them, he said.
In Habiganj, the water level in the Khowai River is flowing 210cm above the danger level at Machulia point of the district town following the onrush of water from hills, said Md Tawhidul Islam, executive engineer of Water Development Board.The town protection dyke stands threatened at different points due to the increase in the water level in the Khowai River.
In Moulvibazar, embankment on the Monu River at Sharifpur union in Kulaura upazila cracked at four points, flooding vast areas and rendering 3,000 people marooned.
Executive engineer of the local Water Development Board Ronendra Shongkar Chakraborti said the Monu River water was flowing 173 centimeters above the danger level.
In Kamarganj upazila, 50 villages were flooded as embankment on the Dhalai River developed cracks at eight points due to incessant rain and onrush of water from hills.
In Feni, 17 villages in Parshuram and Fulgazi upazilas were flooded by the onrush of water from upstream and rain, rendering several thousand people marooned.
WDB executive engineer Kohinur Alam said the Muhuri River at Parshuram point was flowing 80cm above the danger level at 6pm on Tuesday.
Parshuram pourashava mayor Nizamuddin Chowhdury Sajel said vast tracts of land have been flooded due to the collapse of dyke at Sahar Para village in poura area.
In Sylhet, three unions in Jaintapur upazila were inundated by floodwater due to rain and onrush of water from hills.
Water level in the Sari is flowing 59 cm above the danger level.