DRESDEN, Germany (AP) -- Desperate families were plucked from rooftops by helicopters, cars were swept away by raging torrents and levees failed without warning Wednesday as central Europe staggered under an inland ocean of flooding.
Tens of thousands of people had to be evacuated in Germany and the Czech Republic and chemical plants along the mighty Danube and Elbe rivers were hastily shut down. City officials, federal troops and emergency workers across a vast region either raced to prepare or struggled to cope as flood crests roared downstream.
Near the southeastern German town of Deggendorf, two levees broke along the Danube and Isar rivers and their raging waters engulfed nearby houses. A southern German highway disappeared under the muddy floodwaters, cars were swept away and only the top of a few trucks peeked out above the waters.
Families scrambled to their rooftops and were airlifted to safety.
"This is an absolutely life-threatening situation," local firefighter Alois Schraufstetter said. "Houses are covered up to 3 meters (10 feet) deep in water."
Four farmers were rescued at the last minute by a helicopter airlift as floods submerged their tractor, he said. About 2,000 people were evacuated.
"We would have risked our lives had we stayed at home," resident Hans Loefflmann said, adding that he and his wife had to leave all their valuables behind when the floods gushed into their house within minutes.
Firefighters said more than 19,000 people were evacuated from the flooding in the Czech Republic.
In the eastern German city of Halle, the downtown area flooded despite frantic efforts to protect it with sandbag barriers. Authorities urged 30,000 residents to leave their homes as the Saale river reached its highest level in 400 years.
"We fought against the water all day yesterday, and we've lost," said Julia Linne, an employee at an intensive care home in Halle. "At one point we just gave up."
In the Czech Republic, authorities said the water in the Elbe was expected to reach 11 meters (36 feet) early Thursday in the country's north, almost four times its usual height.
After inundating parts of Prague, a surge on the Elbe was now roaring north toward Germany, particularly the eastern city of Dresden, where hundreds were being evacuated. The river, which was expected to crest early Thursday, was running about 7 meters (21 feet) over normal levels Wednesday.
Overall, 16 people have died since the beginning of the flooding last week, including eight people in the Czech Republic, five in Germany, two in Austria and one in Slovakia. At least four other people were missing in the Czech Republic, according to the interior minister.
Hundreds of German police officers and volunteers were helping to fight the floods along with about 5,600 soldiers and 2,000 members of Germany's national disaster team, filling sand bags, reinforcing levees and building elevated walkways to flooded homes.
"In Dresden, we have dozens of members instructing some 300 volunteers on how to build a temporary dam to hold the water back from one of the city's main thoroughfares," disaster team member Carolin Petschke said.
In villages around Usti nad Labem, a city of 100,000 in the northern Czech Republic, police in boats were handing out drinking water and medicine to those who had not evacuated.
Alena Lacinova despaired at how much she would have to rebuild after watching the water wash into her home. In many places, even protective barriers were unable to stop the surge.
"At the moment, we have about 2.5 meters (8 feet) of water inside. The cellar and the house are flooded," she told The Associated Press, adding that she was expecting another meter (3 feet) of water soon. "It's a pity for all those who have the same problem and have not enough money to fix it anytime soon."
Lower parts of Usti nad Labem -- built around a valley -- looked like a ghost town. About 3,000 people had evacuated, while others remained inside their homes on higher ground. Some stood on hilltops, watching the water as it rose. Police patrolled to make sure no looting occurred.
In the Czech capital of Prague, Environment Minister Tomas Chalupa said the city's sewage treatment plant -- which had to be shut down because of high water -- might be operational again in the next 24 hours. Since the shutdown, the city's effluence has gone straight into the Vltava River, which runs through the city.
"It's not over yet," Czech Prime Minister Petr Necas said. "There are tough moments still ahead of us."
He pledged more than 5 billion koruna ($250 million) for cleanup work.
Authorities were also concerned about the safety of chemical plants next to the overflowing rivers. Czech public television said a barrier that protects one major fertilizer plant in Lovosice was leaking Wednesday but Necas visited the plant and downplayed the danger.
"The anti-floods measures are functioning well. The protective means have fulfilled their purpose," he said, adding that all dangerous chemicals had been transported to safety.
Floodwaters were slowly receding in the hard-hit Bavarian city of Passau after reaching levels not seen in 500 years, leaving behind huge amounts of debris.
While most parts of Prague, including its historical landmarks, were protected by high metal barriers, the city's zoo was particularly badly hit for the second time in 11 years. The lower side of the park was submerged and the animals had to be evacuated.
The zoo estimated the damage at $8 million, but insisted it would reopen its higher parts shortly.
"The flood will not break us," it said in a statement.
Jan Gebert reported from Usti Nad Labe, Czech Republic. Juergen Baetz and Kirsten Grieshaber in Berlin and Karel Janicek in Prague contributed to this story.