Severe flooding caused by historic rainfall has led to dozens of deaths in Western Europe, and many other people remained missing as of Thursday.

The German states of Rhineland-Palatinate and North Rhine-Westphalia were worst hit, but Belgium and the Netherlands are also badly affected, with further flooding in Luxembourg and Switzerland, according to the BBC.

Some 15,000 police, soldiers and emergency service workers are reportedly at the scene to aid with search and rescue, while helicopters picked stranded residents from roof tops and tanks cleared roads of fallen trees and debris.

Residents in the region told AFP news agency they were stunned by the disaster.

“In some areas we have not seen this much rainfall in 100 years,”' Andreas Friedrich, a German weather service spokesman, told CNN.

Flash floods have swept across western and southern Germany, causing buildings to collapse, police said.

German Chancellor Angela Merkel has pledged full support for the victims of some of the country's worst flooding in decades.

Speaking during a meeting 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 will only see the full extent of this tragedy in the coming days," she said.  She also pledged government support with rescue efforts and with reconstruction, saying to the German people that the government “will not leave you alone in this difficult, terrible hour,” according to the BBC

At least 59 people have died in Germany with hundreds more reported missing, the BBC reports.

Belgium, Luxembourg, the Netherlands and Switzerland have also been affected by flooding.

The BBC says residents of Liège, Belgium's third-largest urban area after Brussels and Antwerp, were ordered to evacuate. Local officials said those unable to leave should move to the upper floors of their buildings.

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.