Authorities in central Europe are on high alert after torrential rain caused rivers to rise and put pressure on flood defences.
The army has been deployed in Austria, the Czech Republic and Germany to deal record levels of flooding in some areas. Thousands of homes across the region have been evacuated.
Four people have died and at least eight are missing as the rains caused landslides and took rivers to dangerously high levels.
Main roads in many areas of central Europe have been closed and rail services cut. In some areas, electricity has been turned off as a precaution, the BBC reports.
The Czech capital, Prague, is on high alert amid fears that floodwaters could swamp its historic centre on Monday. At risk is the 14th Century Charles Bridge and other buildings close to the river bank.
Underground stations have been closed and businesses and schools shut as city officials braced themselves to see whether the Vltava River would flood its banks. Animals from the city's zoo have also been evacuated.
Prime Minister Petr Necas called a special cabinet session on Sunday to co-ordinate the emergency response and about 1000 troops have been mobilised to help erect metal barriers and fill sandbags. "We will do everything to protect people's lives and health," he said.
Floods in 2002 killed 17 people in the Czech Republic. Water levels have not reached that point yet, but more rain is forecast for another few days.
In Germany, Bavaria's flood alert service warns that the forecast of continuing heavy rain is likely to worsen the flooding affecting the Danube and the Inn, among other rivers in the area.
The German cities of Passau and Rosenheim have declared a state of emergency. Authorities in Passau, which lies at the confluence of three rivers in Bavaria, said waters could rise above the record levels of 2002.
In Austria, the meteorological service said two months worth of rain had fallen in just two days.