At least 170 people have died in floods in western Europe and hundreds remain missing after record rainfall.
Homes have collapsed and streets have been submerged by the weather, which has been blamed on climate change.
Germany has borne the brunt of the deluge, with at least 133 dead. But Belgium, Luxembourg and the Netherlands have also been battered by the storms.
In Germany, where the military has been called in to support rescue efforts, President Frank-Walter Steinmeier visited some of the areas affected.
“We are mourning with all those who lost friends, acquaintances or family members,” he said in the town of Erftstadt, where floods triggered a landslide.
“Their fates break our hearts.”
About 19,000 rescuers have been sent to support aid efforts.
“Whole places are scarred by the disaster,” Mr Steinmeier said before making the visit. “Many people have lost what they have built all their lives.”
Erftstadt, in the state of North Rhine-Westphalia, was one of the hardest-hit areas.
“We have to assume we will find further victims,” said Erftstadt’s mayor, Carolin Weitzel.
While waters are beginning to recede from many of the affected areas, residents are returning to scenes of devastation.
In Schuld, a town in the state of Rhineland-Palatinate, baker Cornelia Schloesser returned to survey the damage after her family’s century-old business was destroyed.
“Within minutes, a wave was in the house. It’s all been a nightmare for 48 hours. We’re going around in circles here but we can’t do anything,” she told AFP.
A burst dam in North Rhine-Westphalia forced about 700 local residents to flee Wassenberg, on the border with the Netherlands.
“Water levels have been stabilising since last night. One can say the situation is stable,” Wassenberg’s mayor, Marcel Maurer, said. “It’s too early to give the all-clear, but we are cautiously optimistic.”
Armin Laschet, the premier of North Rhine-Westphalia, said the flooding was a “catastrophe of historic dimensions”.
“The floods have literally pulled the ground from beneath many people’s feet. They lost their houses, farms or businesses.”
In affected areas, firefighters, local officials and soldiers, some driving tanks, have begun the colossal work of clearing the piles of debris clogging the streets.
Rescue efforts have been complicated by severe disruption to gas, electricity and telephone services.
“The task is immense,” said Tim Kurzbach, mayor of Solingen, a city in the north-west.
Belgium’s prime minister, Alexander de Croo, is visiting areas affected by what he called “unprecedented” flooding in his country, where at least 24 people have died.
He has declared Tuesday a day of official mourning.
On a visit to flood-hit areas in Belgium, European Commission chief Ursula von der Leyen offered EU support.
UAE President Sheikh Khalifa sent condolences to Germany’s leaders.
Sheikh Mohammed bin Rashid, Vice President and Ruler of Dubai, and Sheikh Mohamed bin Zayed, Crown Prince of Abu Dhabi and Deputy Supreme Commander of the Armed Forces, also sent messages of sympathy and concern.
Questions are now being asked about what caused the devastating weather to occur.
Mr Steinmeier called for a more “determined” battle against climate change.
The floods have put climate change at the centre of the campaign to succeed German Chancellor Angela Merkel in the run up to the September elections. Ms Merkel will visit affected areas within days.
Mr Laschet from Ms Merkel’s Christian Democratic Union, and the front-runner to succeed the veteran chancellor, described “a disaster of historic proportions”.
“In the next few days, we as a country will do everything we can to organise the funds that are now needed in direct aid. Here in Erftstadt, money is paid out very un-bureaucratically to people who are in need.”
Dutch Prime Minister Mark Rutte said climate change was “without a doubt” a factor.
“I don’t want to make hasty declarations,” he said. “But something is really happening, let’s be clear.”
To prevent future flood disasters, “the first thing to do, and fortunately we are doing it in the Netherlands, is to give space to rivers”, Mr Rutte said.
After major flooding in 1993 and early 1995, when 250,000 people and one million animals had to flee, the Netherlands reshaped areas around the rivers.
More than €2 billion ($2.4bn) was invested to widen riverbanks, with the project completed in 2019.
“We see that neighbouring countries are saying ‘We must learn still more from the Dutch to deal with the fact that there will be more water in coming years’,” Mr Rutte said.
But he said his country would have to “learn lessons” and ask: “What more can we do?”
The floods wreaked havoc in parts of the south, with thousands of residents unable to return until Saturday morning.
“If you look at Belgium and Germany where people really drowned, collapsed houses, that’s of a different order,” Ijmert Kant, who lives in the town of Brommelen, told AP.