Thousands of eastern Germany residents were ordered from flood-threatened homes Thursday as emergency crews in Dresden, joined by parents and their children, piled sandbags around the rising Elbe River to protect a city renowned fors its cultural treasures.

Authorities stepped up evacuations in Dresden even as sunshine returned to the region. The Elbe kept rising ahead of its expected cresting Friday, prompting officials to order residents in the outlying Gohlis district to leave their homes because of fears that a dike could fail.

After nightfall, police ordered about 5,000 people from their homes in another part of Dresden about 4 miles downstream from the historic center, Saxony state officials said.

Two other neighborhoods -- the closest yet to the historic city center -- also were ordered evacuated after nightfall, but no figures on the number of people affected were released.

Security officials hoped to move about 30,000 people from their homes in and around the town of Pirna, 12 miles south of Dresden, by early Friday.

In other cities downstream, emergency officials pressed ahead with evacuation plans for tens of thousands more residents along rain-swollen rivers and tributaries.

A huge chemical industry complex about 70 miles to the north came under threat after a raging river broke through a levee, but officials said the plants at Bitterfeld -- a notoriously polluted site during communist East German times -- were not at risk. An evacuation of the town was called off.

At least 100 people have died in Europe's flooding. Most casualties were in Russia, where the death toll stood at 59 -- mostly Russian tourists vacationing on the Black Sea who were swept away by swiftly moving water. On Thursday, weather forecasters predicted new storms on the Black Sea coast.

Chancellor Gerhard Schroeder, struggling in his campaign for a second term in Sept. 22 elections, spoke of a "national catastrophe" and promised to spearhead a rebuilding effort he said would cost billions of dollars.

"These must be mobilized, and we are determined to do that," Schroeder said, though he gave no specifics on where the money would come from.

In Dresden, Mayor Ingolf Rossberg said the Elbe River rose above 26 feet to its highest level in more than 100 years. It had yet to burst its banks in the city center, but officials said the river -- fed by high water that earlier devastated Prague -- was expected to crest Friday.

Dresden residents barricaded streets along the Elbe's banks with sandbag walls Thursday, with adults and children passing bags in a chain. Some children struggled under the weight of the bags, as chairs, tables and branches floated by in the dirty brown river.

Richard Schutze, his hands cut from hauling the burlap sacks, said the neighborhood was working all day to protect their homes.

"You have to always add more. Every half an hour we added another layer, but it's hard to say if it's enough," he said. "This water is extreme."

Downstream from Dresden to the north, several cities on the Elbe -- notably Magdeburg -- braced for their share of flooding that has left 11 dead in Germany.

To the southeast in Europe, the rising Danube raised alarm. It was expected to peak Friday in Bratislava, the Slovak capital, and on Sunday in Budapest, Hungary. In Austria, where the floods left seven dead, the capital Vienna was spared major flooding as the Danube receded.

Among the Dresden landmarks under renewed threat were the Baroque city's famed 19th-century Semper Opera and the Renaissance-style Zwinger Gallery museum, already hit by earlier flooding. The city's waterlogged main train station has been closed for days.

Largely destroyed by a February 1945 Allied fire bombing near the end of World War II, rebuilt Dresden is one of Germany's top cultural attractions and tourist spots. Many of the landmarks are near the banks of the Elbe.

In Dresden's numerous museums, volunteers and firefighters have helped carry more than 4,000 paintings out of basements to safer ground this week.

Four large paintings in the Zwinger basement were too bulky to carry, so workers hung them from the ceiling, said Steffen Grosse, a spokesman for the state culture ministry. Water was being pumped from the basement, he said.

Stage machinery was damaged in the Semper Opera's flooded basement and sets damaged, Christoph Bauch of the technical staff said. But the stage above was intact, he said.

Officials had ordered the evacuation of Bitterfeld's 16,000 residents as the Mulde river, an Elbe tributary, threatened the chemical industry town. But authorities later called off the order.

Most of the water spill rushed into old open strip mines, and emergency services official Reiner Jacob said threatening waters were receding late Thursday. "The chemical park is not in danger at this time," he said.

Waters receded in Prague, where thousands of sandbags kept the raging river from punching through and flooding the historic Czech capital's Old Town.

Czech Prime Minister Vladimir Spidla said Thursday that 5,000 soldiers would be deployed to help mop up after the devastating floods. Actor Sean Connery, who was in Prague shooting a film during the height of the flooding Wednesday, said he was left speechless by the damage.

"I couldn't adequately express the disaster that it is now," he said.

Famed Czech brewery Budejovicky Budvar resumed production of the original Budweiser on Thursday, two days after unprecedented flooding shut down operations, officials said.

Concern grew in Germany on Thursday about possible contamination of the Elbe from a flooded chemical plant in the Czech Republic. German Environment Minister Juergen Trittin, on a brief visit to Dresden, said he had no evidence so far that the plant at Neratovice posed a danger.

However, Czech officials said Thursday that a cloud of chlorine gas was released from the plant. Karolina Sulova, an Environment Ministry spokeswoman, said chlorine levels in villages near the town were being monitored and no health threat was immediately detected.

In the Czech province of South Bohemia, the flood-swollen Otava River tore a decorative statue, railings and stones Thursday from the country's oldest stone bridge, a 13th-century span in Pisek.