At 10.30 pm, police, militia and residents joined forces under heavy rain to reinforce the dike using sand bags.
Xuan Mai Commune Chairman Nguyen Anh Duc was on site to direct the work.
Rising waters in the Tich, Bui and Day rivers had already flooded homes in Bui Xa village by 8 pm, with water levels reaching 20 to 30 centimeteres and forcing families to relocate.
The Northern Hydrometeorological Centre warned that flood peaks on the Bui and Tich rivers could surpass level 3 alerts, threatening low-lying areas with prolonged inundation for two to three days.
Bui Xa, located next to the Bui River, is a flood discharge zone of Xuan Mai Commune and home to 120 households with nearly 500 residents.