Record rainfall causing rivers to burst in Germany and Belgium killed at least 70 people.
According to official figures, most of the victims were reported in Germany, but at least 11 died in Belgium.
More people have also been reported missing in both countries.
The Netherlands was also severely affected by the heavy rains, local authorities said.
The German states of Rhineland-Palatinate and North Rhine-Westphalia suffered the most severe damage.
Local officials said the heavy rainfall was caused by climate change.
During a visit to a hard-hit area, North Rhine-Westphalia Prime Minister Armin Laschet blamed extreme global warming, saying the events would repeat.
“We will be faced with such events over and over, and that means we need to speed up climate protection measures… because climate change isn’t confined to one state,” he stated.
But experts say it’s complicated to link a single event to global warming even though climate change increases abrupt and extreme weather changes’ frequency.
Heavier rains are also forecast across the region today.
In Germany, police helicopters and hundreds of soldiers have been deployed to the worst-hit areas to help stranded residents.
Dozens of people have been rescued from the rooftops.
Besides, authorities have ordered to close schools across the country’s west region as transportation systems have been severely disrupted.
In the district of Schuld bei Adenau in the mountainous Eifel region, around 25 houses were in danger of collapsing, and some properties have been cut off as they could not be accessed by boat.
German Chancellor Angela Merkel, who recently traveled to the United States for a meeting with President Joe Biden, called the flooding a “catastrophe.”
Ms. Merkel asked residents to trust that federal, regional and community government forces would work together to save lives, alleviate the danger and ease distress.
Meanwhile, dramatic footage of the floods shared on social media showed cars dragged through Verviers city’s streets in Belgium.
Local authorities ordered residents of the country’s third-largest urban area, Liège, to evacuate or move to their buildings’ upper floors if they cannot leave.
It was also reported that the Meuse River, which flows through the city and is about to overflow, could rise 1.5 meters more.
People residing in the Belgian town of Pepinster, located at the two rivers’ confluence in the Liège province, were also evacuated on Thursday.
In the Trooz municipality, conditions have been so bad that evacuation efforts were hampered and had to be halted.
Although no casualties have been reported, officials in the Netherlands have urged thousands of people in different locations along the Meuse River to leave their homes quickly.
Moreover, 10,000 people were evacuated in the Dutch city of Maastricht and flooding in Valkenburg forced several nursing homes to evacuate.