MAGLAJ, Bosnia-Herzegovina — Packed into buses, boats and helicopters, carrying nothing but a handful of belongings, tens of thousands fled their homes Saturday in Bosnia and Serbia to escape the worst flooding in a century.
Rising rivers surged into homes, sometimes reaching up to the second floors, sending people climbing to rooftops for rescue.
Hundreds were also evacuated in Croatia.
Authorities said 20 people have died but warned the death toll could rise. Tens of thousands of homes were left without electricity or drinking water.
Landslides triggered by the floods also raised the risk of injury or death from land mines left over from Bosnia's 1992-95 war. The landslides swept away many of the carefully placed warning signs around the minefields.
Three months' worth of rain fell on the region in three days last week, creating the worst floods since records began 120 years ago.
Observed from the air, almost a third of Bosnia, mostly its northeast corner, resembled a huge muddy lake, with houses, roads and rail lines submerged. Admir Malagic, a spokesman for Bosnia's Security Ministry, said about a million people — over a quarter of the country's population — live in the affected area.
"Bosnia is facing a horrible catastrophe," said Bakir Izetbegovic, the chairman of the Bosnian three-man presidency. "We are still not fully aware of actual dimensions of the catastrophe."
Izetbegovic was touring Maglaj, hard hit by floods. As the waters mostly withdrew on Saturday, Maglaj was covered in mud and debris, with residents checking damage and bringing furniture out in the streets to dry.
"Everything is destroyed, but we are happy to be alive," said Maglaj resident Zijad Omerovic.
In the eastern Bosnian town of Bijeljina, some 10,000 people were being evacuated Saturday after the rain-swollen Sava River pushed through flood defenses, endangering four villages outside the town.
In eastern Croatia, the overflowing Sava spread over villages and farmland, sending hundreds fleeing.
Officials in Bosnia say 12 people died and more bodies could be found as water recedes from dozens of cities. In some places, people had to be rescued by helicopter from their roofs.
In Serbia, eight deaths were reported and emergency crews and soldiers were using boats and helicopters to rescue thousands trapped in the town of Obrenovac, near Belgrade. Authorities also ordered residents of another nearby small town, Baric, to leave.
Officials said more than 16,000 people have been evacuated from flood-hit regions in Serbia, many finding shelter in schools and sports halls.