Devastating floods have torn through entire villages and killed at least 128 people in Europe, most of them in western Germany where stunned emergency services were still combing the wreckage on Friday.

Unsuspecting residents were caught completely off guard by the torrent dubbed the "flood of death" by German newspaper Bild.

Thousands of emergency responders including soldiers were deployed in western Germany
Thousands of emergency responders including soldiers were deployed in western Germany AFP / INA FASSBENDER

Streets and houses were submerged by water in some areas, while cars were left overturned on soaked streets after flood waters passed. Some districts were completely cut off.

"Everything was under water within 15 minutes," Agron Berischa, a 21-year-old decorator from Bad Neuenahr in Rhineland-Palatinate state, told AFP.

"Our flat, our office, our neighbours' houses, everywhere was under water."

Some towns in Germany were completely underwater
Some towns in Germany were completely underwater DPA / Sebastian Schmitt

In nearby Schuld, Hans-Dieter Vrancken, 65, said "caravans, cars were washed away, trees were uprooted, houses were knocked down".

"We have lived here in Schuld for over 20 years and we have never experienced anything like it. It's like a warzone," he said.

Roger Lewentz, interior minister for Rheinland-Palatinate, told Bild the death toll was likely to rise as emergency services continued to search the affected areas over the coming days.

Thousands were evacuated from flooded areas in the Netherlands
Thousands were evacuated from flooded areas in the Netherlands ANP / Sem van der Wal

"When emptying cellars or pumping out cellars, we keep coming across people who have lost their lives in these floods," he said.

With five more dead found in the state by Friday evening, the nationwide death toll mounted to 108.

The floods have put climate back at the top of the agenda in Germany ahead of a changing of the guard as Angela Merkel steps down
The floods have put climate back at the top of the agenda in Germany ahead of a changing of the guard as Angela Merkel steps down AFP / SAUL LOEB

Adding to the devastation, several more people were feared dead in a landslide in the town of Erftstadt in North Rhine-Westphalia (NRW) triggered by the floods.

In neighbouring Belgium, the government confirmed the death toll had jumped to 20 -- earlier reports had said 23 dead -- with more than 21,000 people left without electricity in one region.

Calling the floods "possibly the most catastrophic our country has ever seen," Prime Minister Alexander De Croo declared Tuesday a day of national mourning.

The massive flooding in western Germany has left dozens of people dead and caused significant damage
The massive flooding in western Germany has left dozens of people dead and caused significant damage NEWS5 / Michelle FITZPATRICK

Luxembourg and the Netherlands were also hammered by heavy rains, inundating many areas and forcing thousands to be evacuated in the city of Maastricht.

Residents assessed the damage in Belgium, where more than 21,000 people had no electricity in one area
Residents assessed the damage in Belgium, where more than 21,000 people had no electricity in one area BELGA / BRUNO FAHY

In Germany's hard-hit Ahrweiler district in Rhineland-Palatinate, several houses collapsed completely, drawing comparisons to the aftermath of a tsunami.

At least 24 people were confirmed dead in Euskirchen, one of the worst-affected towns.

"I fear that we will only see the full extent of the disaster in the coming days," Chancellor Angela Merkel said late Thursday from Washington, where she met with President Joe Biden.

Residents assessed the damage in Belgium, where more than 21,000 people had no electricity in one area
Residents assessed the damage in Belgium, where more than 21,000 people had no electricity in one area BELGA / BRUNO FAHY

"My empathy and my heart go out to all of those who in this catastrophe lost their loved ones, or who are still worrying about the fate of people still missing."

In Ahrweiler, around 1,300 people were unaccounted for, although local authorities told Bild the high number was likely due to damaged phone networks.

Lewentz told local media that up to 60 people were believed to be missing, "and when you haven't heard from people for such a long time... you have to fear the worst".

Gerd Landsberg, head of the German Association of Towns and Municipalities, said the cost of the damage was likely to run into "billions of euros".

In Belgium, the army has been sent to four of the country's 10 provinces to help with rescue and evacuations.

The swollen Meuse river "is going to look very dangerous for Liege", a nearby city of 200,000 people, warned Wallonia regional president Elio Di Rupo.

In Switzerland, lakes and rivers were also swelling after heavy overnight rainfall. In Lucerne in particular, Lake Lucerne had begun to flood the city centre.

Some parts of western Europe received up to two months' worth of rainfall in two days on soil that was already near saturation, according to the World Meteorological Organization.

But there was some improvement Friday as the water level began to fall back.

The severe storms have put climate change back at the centre of Germany's election campaign ahead of a September 26 poll marking the end of Merkel's 16 years in power.

Speaking in Berlin, President Frank-Walter Steinmeier said Germany would "only be able to curb extreme weather situations if we engage in a determined fight against climate change".

The country "must prepare much better" in future, Interior Minister Horst Seehofer said, adding that "this extreme weather is a consequence of climate change".

Because a warmer atmosphere holds more water, climate change increases the risk and intensity of flooding from extreme rainfall.

North Rhine-Westphalia premier Armin Laschet, the conservative running to succeed Merkel, called for "speeding up" global efforts to fight climate change, underlining the link between global warming and extreme weather.