At least five people died on Wednesday in flooding across France and Germany, authorities say.
Search teams in the Bavarian town of Simbach am Inn found the bodies of three people who had been trapped in a house and a woman was found dead by a nearby stream. In central France an 86-year-old woman lost her life.
Dozens of towns have been inundated and people have been saved by helicopter.
Forecasters say waters are expected to keep rising for several days.
The floods are thought to have caused substantial damage.
The worst affected area in southern Germany is the district of Rottal Inn, where a disaster centre has been established.
In the town of Triftern, rivers and streams burst their banks. Floodwaters dragged along cars, trees and furniture from flooded homes.
In many places the water reached several metres above street level. The inhabitants, surprised by the sudden flooding, had to be rescued by helicopter.
However, 250 children who had been trapped in a school in Triftern over Tuesday night were able to leave the building on Wednesday evening, officials said.
A further 350 pupils in Simbach am Inn were also brought to safety and a refugee shelter in the town was evacuated.
No relief in sight - Jacob Cope, forecaster, BBC Weather Centre
A large area of low pressure has been bringing heavy showers to much of Europe recently and this weather pattern shows no signs of shifting in the next few days.
A large swathe of the continent from central France through Belgium, Germany through southern Poland to Romania, Moldova and Ukraine looks set for further heavy, thundery showers to end the week and through the weekend.
These showers are likely to be slow moving and have the potential to be long-lasting with large hailstones, frequent lightning, gusty winds and flash flooding with as much as 50mm (2 in) of rain in some parts in just a few hours.
The floods were also declared an emergency in the historic town of Passau, on the border with Austria, the scene of massive flooding three years ago.
In nearby Pfarrkirchen more than 35 litres of water per square metre fell in the space of six hours on Wednesday, according to the German meteorological office.
More thunderstorms are forecast for southern Germany, and water levels on some rivers are predicted to rise further still.
In France, the town of Nemours, near Paris, had to be evacuated. Interior Minister Bernard Cazeneuve said emergency workers had carried out more than 8,000 rescue operations over two days between the Belgian border and the Burgundy region.
Nemours resident Sylvette Gounaud told Agence France-Presse: "In 60 years of living here, I've never seen this. The centre of town is totally under water. All the shops are destroyed."
Central France has seen some of its worst flooding in 100 years. The Loiret area received the average rainfall of six weeks in three days.
The body of the 86-year-old woman was found in her flooded house in Souppes-sur-Loing.
One street in Montargis, south of Paris, was turned into a canal.
The high level of the Seine in Paris led to the closure of many promenades, amid fears the water could rise another metre in coming days.
Some 10,000 emergency call-outs have been made by fire services nationwide since Sunday.