Michelle Fitzpatrick with Deborah Cole in Berlin
Mayen, Germany - Heavy rains and floods lashing western Europe have killed at least 45 people in Germany and left many more missing, as rising waters led several houses to collapse on Thursday.
Unusually heavy rains also inundated neighbouring Luxembourg, the Netherlands and Belgium, where at least four people were reported dead and people were ordered to evacuate a riverbank in one city.
In Germany, which is experiencing one of the worst weather disasters since the Second World War, desperate residents sought refuge on the roofs of their homes as rescue helicopters circled above.
Pensioner Annemarie Mueller, 65, looking out at her flooded garden and garage from her balcony, said her town of Mayen had been completely unprepared for the destruction.
"Where did all this rain come from? It's crazy," she told AFP, recalling the floodwater crashing through her street during the night.
"It made such a loud noise and given how fast it came down, we thought it would break the door down."
Chancellor Angela Merkel, on a visit to Washington, said she was "shocked" by the humanitarian "disaster", calling it a "tragedy" for the nation.
She vowed that the government would do "everything in its power to, under the most difficult circumstances, save lives, prevent danger and ease suffering".
North Rhine-Westphalia (NRW) premier Armin Laschet, who is running to succeed Merkel in September elections, cancelled a party meeting in Bavaria to survey the damage in his state, Germany's most populous.
"We will stand by the towns and people who've been affected," Laschet, clad in rubber boots, told reporters in the town of Hagen.
He called for "speeding up" global efforts to fight climate change, underlining the link between global warming and extreme weather.
Because a warmer atmosphere holds more water, climate change increases the risk and intensity of flooding from extreme rainfall.
Nineteen bodies were recovered in the region around the western town of Ahrweiler alone, with up to 70 people missing, a police spokesman told AFP.
Farther north, the district of Euskirchen in NRW reported 15 dead. Four more victims were found in the municipality of Schuld south of Bonn where six houses were swept away by floods.
Several other bodies were recovered from flooded cellars across the region.
The environment ministry in Rhineland-Palatinate state warned it expected floodwaters on the Rhine and Moselle rivers to rise with more rainfall.
In NRW and Rhineland-Palatinate, some 200,000 households were without power.
Police set up a crisis hotline for reporting missing loved ones and residents were asked to send in videos and photos that could help them in the search.
Regional official Juergen Pfoehler in Ahrweiler urged people to stay home "and, if possible, go to higher floors" of their houses.
The German military deployed some 400 soldiers across the two affected states to assist in rescue efforts.
In the city of Leverkusen, a power outage triggered by the storms led to the evacuation of a hospital with 468 patients.
Belgium has also seen several days of heavy rain that has caused rivers in the French-speaking region of Wallonia to burst their banks. Four were reported dead.
The provinces of Liege and Namur were especially affected, with the resort town of Spa completely flooded.
Residents in Liege were told Thursday to urgently evacuate neighbourhoods near the banks of the Meuse river.
In the town of Chaudfontaine, daily Le Soir reported that nearly 1,800 people had to evacuate.
The country's Infrabel rail network said it was suspending services in the southern half of the country, given the risks to travel.
Meanwhile Dutch safety workers have evacuated hundreds of homes in the southern town of Roermond.
Officials also closed off several roads including the busy A2 highway, while fears remained that water from heavy rains in Germany and Belgium would push up river levels as it reached the Netherlands.
The Luxembourg government set up a crisis cell to respond to emergencies triggered by heavy rains overnight as Prime Minister Xavier Bettel reported "several homes" had been flooded and were "no longer inhabitable".