More than 60 people have died and dozens were missing Thursday (local time) in Germany and Belgium as heavy flooding turned streams and streets into raging torrents that swept away cars and caused houses to collapse.
Recent storms across parts of western Europe made rivers and reservoirs burst their banks, triggering flash floods overnight after the saturated soil couldn't absorb any more water.
"I grieve for those who have lost their lives in this disaster," German Chancellor Angela Merkel said during a visit to Washington, expressing shock at the scope of the flooding. "We still don't know the number. But it will be many."
She pledged that everything would be done to find those still missing, adding: "'Heavy rain and flooding' doesn't capture what happened."
Police said 18 people died in Ahrweiler county, 15 in Euskirchen, three in Rheinbach and two in Cologne. Belgian media reported four deaths in that country.
Among the worst-hit German villages was Schuld, where several homes collapsed and dozens of people remained unaccounted for.
Rescue operations were hampered by blocked roads and phone and internet outages across the Eifel, a volcanic region of rolling hills and small valleys. Some villages were reduced to rubble as old brick and timber houses couldn't withstand the sudden rush of water, often carrying trees and other debris as it gushed through narrow streets.
Karl-Heinz Grimm, who had come to help his parents in Schuld, said he had never seen the small Ahr River surge in such a deadly torrent. "This night, it was like madness," he said.
Dozens of people had to be rescued from the roofs of their houses with inflatable boats and helicopters. Germany deployed hundreds of soldiers to assist.
"There are people dead, there are people missing, there are many who are still in danger," the governor of Rhineland-Palatinate state, Malu Dreyer, told the regional parliament. "We have never seen such a disaster. It's really devastating."
In Belgium, the Vesdre River spilled over its banks and sent water churning through the streets of Pepinster, near Liege.
"Several homes have collapsed," Mayor Philippe Godin told RTBF network. It was unclear whether everyone had been able to escape unhurt.
Major highways were inundated in southern and eastern parts of the country, and the railway said all trains were halted.
In Liege, a city of 200,000, the Meuse River overflowed its banks Thursday and the mayor asked people living nearby to move to higher ground.
European Union Commission President Ursula von der Leyen pledged to help, tweeting: "My thoughts are with the families of the victims of the devastating floods in Belgium, Germany, Luxembourg and the Netherlands and those who have lost their homes."
The full extent of the damage was still unclear, with many villages cut off by floods and landslides that made roads impassable. Videos on social media showed cars floating down streets and houses partially collapsed.
Many of the dead were only discovered after floodwaters receded.
Authorities in the Rhine-Sieg county south of Cologne ordered the evacuation of several villages below the Steinbachtal reservoir amid fears a dam could break.
Two firefighters died in rescue operations in North-Rhine Westphalia, Germany's most populous state.
Governor Armin Laschet paid tribute to them and pledged swift help for those affected.
"We don't know the extent of the damage yet, but we won't leave the communities, the people affected alone," he said during a visit to the flood-hit city of Hagen.
Laschet, a conservative who is running to succeed Merkel as chancellor in this fall's election, said the unusually heavy storms and an earlier heat wave could be linked to climate change.
Political opponents have criticised Laschet, the son of a miner, for supporting the region's coal industry and hampering the expansion of wind power during his tenure.
Stefan Rahmstorf, a professor of ocean physics at the Potsdam Institute for Climate Impact Research, said it was unclear whether the extreme rainfall seen in Germany was a direct result of planetary warming.
"But one can state that such events are becoming more frequent due to global warming," he told The Associated Press, noting that warmer air can absorb more water vapor that eventually falls as rain.
"The increase in heavy rain and decrease in days with weak rain is now also clearly seen in observational data, especially in the mid-northern latitudes, which includes Germany," Rahmstorf said.
The weakening of the summer circulation of the atmosphere, causing longer-lasting weather patterns such as heat waves or continuous rain, might also play a role, he added.
Rainfall eased later Thursday across Germany, although water levels on the Mosel and Rhine rivers were expected to continue rising.
Authorities in the southern Dutch town of Valkenburg, near the German and Belgian borders, evacuated a care home and a hospice overnight amid flooding that turned the tourist town's main street into a river, Dutch media reported.
The Dutch government sent about 70 troops to the southern province of Limburg late Wednesday to help with evacuations and filling sandbags.
A section of one of the country's busiest highways was closed due to rising water and Dutch media showed a group of tourists being rescued from a hotel window with the help of an earth mover.
In northeastern France, heavy rains flooded vegetable fields, many homes and a World War I museum in Romagne-sous-Montfaucon. Firefighters evacuated people from campgrounds around the town of Fresnes-en-Woevre, according to the local firefighter service. Bastille Day fireworks were canceled in some small towns.
The Aire River rose to its highest levels in 30 years in some areas, according to local newspaper L'Est Republicain.
The equivalent of two months of rain has fallen in some areas over two days, according to the French national weather service, with flood warnings issued for 10 regions. No injuries or deaths have been reported, but forecasters warned of mudslides and more rain on Friday.
A train route to Luxembourg was disrupted, and firefighters evacuated dozens of people near the Luxembourg-German border and in the Marne region, according to broadcaster France Bleu.