Thirty-three people died on Thursday and many were missing as flooding in western Germany caused the collapse of at least six houses, bringing the death toll in two days of severe storms to six.
Police said four people had died and 70 were missing around the wine-growing hub of Ahrweiler, south of Bonn, after the Ahr river, which flows into the Rhine, burst its banks and brought down the houses.
Around 50 were stranded on roofs, and more houses were at risk of collapse.
One local man fled to safety after a flood warning was issued at 2 a.m. (0000 GMT).
"I've never experienced a catastrophe where the river burst its banks in such a short space of time," the 63-year-old man, whose name was not given, told SWR television.
Video footage from nearby Bad Neuenahr showed cars and trucks strewn across streets and one sport-utility vehicle perched on a fence, a road blocked by wreckage and fallen trees as flood waters receded on Thursday morning.
A police spokesperson in Koblenz said firefighters and rescue workers had been widely deployed. "We don't yet have a very precise picture because rescue measures are continuing," the spokesperson said.
Malu Dreyer, premier of the Rhineland-Palatinate state that is home to Ahrweiler, said the region had been hard hit by the flooding.
"It's a catastrophe! There are dead, missing and many people still in danger. All of our emergency services are in action round the clock and risking their own lives," said Dreyer. "I extend my sympathies to the victims of this flood catastrophe."
Dreyer said she would visit the scene of the flooding on Thursday and, in a statement, described some of the dangerous rescue operation. One police helicopter was deployed late on Wednesday to winch people to safety.
Two firefighters died in the Sauerland region, in the neighboring state of North Rhine-Westphalia, on Wednesday, police said. News agency DPA said one had drowned and a second had collapsed after a rescue operation.
State premier Armin Laschet, who is the conservative candidate to succeed Angela Merkel as chancellor at a general election in September, was due on Thursday morning to visit the town of Hagen which has also been hit by flooding.
Rail and road transport were disrupted, and shipping on parts of the Rhine, an important trade artery, was suspended.
More heavy rain was due in southwestern Germany, on the upper reaches of the German Rhine, on Thursday and Friday, the German Weather Service said.