At least 80 people have died and hundreds more are unaccounted for in Germany after a number of the worst flooding in decades.
Record rainfall in western Europe caused rivers to burst their banks, devastating the region.
Belgium has also reported a minimum of 11 dead after the acute weather, which political leaders have blamed on global climate change.
German Chancellor Angela Merkel has pledged full support for the victims.
Armin Laschet, the premier of North Rhine-Westphalia, blamed the acute weather on heating during a visit to a hard-hit area.
“We are going to be faced with such events over and over, which means we’d like to hurry up climate protection measures… because global climate change isn’t confined to at least one state,” he said.
Experts say that global climate change is predicted to extend the frequency of utmost weather events, but linking any single event to heating is complicated.
PICTURES: Floods kill dozens in Germany and Belgium
The German states of Rhineland-Palatinate and North Rhine-Westphalia were the worst hit, but Belgium and therefore the Netherlands also are badly affected, with further flooding in Luxembourg and Switzerland.
In the district of Ahrweiler, many people are unaccounted for, the authorities say. A spokeswoman for the government said mobile networks had been put out of action, making it impossible to contact many of us.
The village of Schuld (population 700) was almost entirely destroyed.
More heavy rain is forecast across the region on Friday.
Some 15,000 police, soldiers, and emergency service workers are at the scene to assist with search and rescue, while helicopters picked stranded residents from rooftops and tanks cleared roads of fallen trees and debris.
Residents within the region told the AFP press agency they were stunned by the disaster.
“Nobody was expecting this – where did all this rain come from? It’s crazy,” Annemarie Mueller, a 65-year-old resident of Mayen, said. “It made such a bang and given how briskly it decreased we thought it might break the door down.”
Floods cause havoc in the German town
Drag button to ascertain destruction in Bad Neuenahr-Ahrweiler.Speaking during a gathering with US President Joe Biden in Washington DC, Mrs. Merkel expressed her “deepest condolences” to everyone across the region who had lost loved ones after “a day of worry and despair”.
“I fear we’ll only see the complete extent of this tragedy within the coming days,” she said. She also pledged government support with rescue efforts and with reconstruction, saying to the German folks that the govt “will not leave you alone during this difficult, terrible hour”.
In Belgium, dramatic footage of the floods showed cars being caught in a frenzy along a street within the city of Verviers.