Authorities say 15 people have died and at least four others are missing in the floods that have ravaged central Europe.

Firefighters said more than 19,000 people have been evacuated from the flooding in the Czech Republic. One raging flood that inundated parts of Prague is now heading north toward Germany.

The dead included eight people in the Czech Republic, four in Germany, two in Austria and one in Slovakia.

Authorities are now concerned about the safety of chemical plants next to the swollen rivers. The plants have been shut down and their chemicals removed.

Hundreds were being evacuated in the German city of Dresden, where the Elbe river is expected to crest later.

More than 3,000 people have had to leave their homes in the Czech city of Usti nad Labem on the Elbe River near the German border, where floodwaters are still on the rise.

High water had already submerged parts of the city as well as many other towns along the Elbe, the biggest river in the country.

"It's not over yet," Czech Prime Minister Petr Necas said. "There're tough moments still ahead of us."

He pledged more than five billion koruna (£162 million) for clean-up work.

Czech public television said a barrier that protects one major chemical plant in Lovosice was leaking. Necas is scheduled to visit the plant later.

Downstream, hundreds of people were being evacuated in the German city of Dresden, where the Elbe is expected to crest this evening. Early in the day it was running about seven meters (21 feet) over normal levels.

In the eastern German city of Halle, the central area was already flooded. Elsewhere in the affected regions, soldiers and residents were reinforcing soaked levees with sand bags to keep them from breaking.

The water was slowly receding in the hard-hit Bavarian city of Passau, leaving behind vast amounts of debris. Flooding earlier this week in Passau was the worst in 500 years.

In the Czech capital of Prague, the level of the swollen Vltava river was dropping and authorities surveyed the damage.

While most parts of the city, including its historical landmarks, were well protected by high metal barriers, Prague's Zoo was particularly badly hit for a second time in 11 years. The lower side of the park was submerged and animals had to be evacuated.