At least six people have reportedly lost their lives to severe floods in western Germany, while several people have also been reported missing in the region by police.
Experts say that climate change is expected to increase the frequency of extreme weather events, but linking any single event to global warming is complicated.
Rhineland-Palatinate was worst hit by the floods where over 50 people have been waiting on rooftops to be rescued.
Local news report that about 30 people were missing in the hilly Eifel region after several homes collapsed due to the floods.
Much of the flooding was triggered when the Ahr river, which flows into the Rhine burst its banks south of Bonn.
Malu Dreyer, chief of the Rhineland-Palatinate state, described the flooding as a “catastrophe”.
“There are dead, missing and many people still in danger,” she said. “All of our emergency services are in action round the clock and risking their own lives.”
Police helicopters and the army have been deployed to some areas to help stranded residents.
Some schools have been closed, while rail and road transport links have been severely disrupted around the west of the country.
A man carries a dog next to debris brought by the flood
About 25 houses are in danger of collapsing in the district of Schuld bei Adenau in the Eifel region, where a state of emergency has been declared.
Four people died in the Eifel region when their homes were swept away in the early hours of Thursday, police said.
Meanwhile, two firefighters died on Wednesday in the neighbouring state of North Rhine-Westphalia. One drowned, while the other reportedly collapsed following a rescue operation.
Neighbouring Belgium has also been hit by flash floods, and dramatic video showed cars being swept away along a street in the city of Verviers.
Almost 2,000 people have been forced to evacuate in the town of Chaudfontaine, the Le Soir newspaper reported.
Rail services in the southern half of Belgium have been suspended because of the extreme weather.
In the Netherlands, the province of Limburg has been left heavily flooded following downpours overnight.
Forecasts suggest more heavy rain is due in Germany and Belgium on Thursday and Friday.