Story highlights Damage is in the billions of euros, according to first day of assessment in Bosnia

EU warns of massive ecological damage from flooding after thousands of landslides

At least 13 people in Serbia and 13 in Bosnia and Herzegovina are dead after epic flooding

The Red Cross says shifting landmines could endanger rescuers and residents

As if the deadly flooding inundating much of the Balkans wasn't alarming enough, rescuers must now grapple with another concern: the risk of landmines from the Bosnian war resurfacing.

"A vast number of landslides have worsened the situation and relief efforts," the Red Cross said , describing the rains as the "worst floods in more than a century."

The epic flooding is the worst Serbia has seen since the country began keeping records 120 years ago, meteorologists said.

"There are reports that landmines buried during the conflict and not yet removed are in some instances being shifted with the landslides, adding (to) the dangers of people living in the areas as well as rescuers," the Red Cross said.

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"We cannot say exactly what happened with the mine fields," Bosnian President Bakir Izetbegovic told CNN's Christiane Amanpour. He warned that the mines were likely displaced in the flooding along with signs warning of mines in the area. "The system of the mine fields (was) under control, and had warnings marks are now actually removed," Izetbegovic said.

In the Serbian town of Obrenovac, at least 13 bodies have been recovered, and officials in Bosnia-Herzegovina said 13 people had died there so far. Expert predict those numbers to rise as flood waters recede.

Photos: Photos: Record flooding in Balkans Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Bosnian workers inspect the damage on heavy machinery after devastating flooding at a coal mine in the village of Sikulje on Thursday, May 22. Heavy rainfall in Serbia and neighboring Bosnia-Herzegovina has resulted in the worst flooding since records began 120 years ago, meteorologists say. Hide Caption 1 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Dogs from the flood-hit town of Obrenovac stay in a shelter in Belgrade, Serbia, on May 22. Hide Caption 2 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A woman rides a bicycle past a flooded cemetery in Domaljevac, Bosnia-Herzegovina, on Wednesday, May 21. Hide Caption 3 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A rescued dog rests in an animal shelter in Drazevac, Serbia, on May 21. Hide Caption 4 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Residents clean streets of mud and rubble after a landslide in Topcic Polje, Bosnia-Herzegovina, on Tuesday, May 20. Hide Caption 5 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Bosnian soldiers repair land-mine warning signs in fields near the banks of the Bosnia River, which flooded near the town of Visoko, Bosnia-Herzegovina, on May 20. Hide Caption 6 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A man walks past a damaged house in Krupanj, Serbia, on May 20. Hide Caption 7 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A man holds dead livestock near Samac, Bosnia-Herzegovina, on May 20. Hide Caption 8 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Floodwaters overtake Obrenovac, Serbia, on Monday, May 19. Hide Caption 9 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Floodwaters surround houses in Obrenovac on May 19. Hide Caption 10 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Police officers help an elderly women get out of a vehicle in Obrenovac on May 19. Hide Caption 11 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – People take shelter at a sports center in Odzak, Bosnia-Herzegovina, on May 19. Hide Caption 12 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – People walk past damaged houses in Krupanj on Sunday, May 18. Hide Caption 13 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Residents place sandbags on a road near Orasje, Bosnia-Herzegovina, to protect the city from flooding on May 18. Hide Caption 14 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – An aerial photo shows the flooding in Brcko, Bosnia-Herzegovina, on May 18. Hide Caption 15 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A woman walks past sandbags along the banks of the Sava River, in the Serbian city of Sremska Mitrovica on May 18. Hide Caption 16 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Police officers help a villager evacuate his farm in anticipation of flooding in Sremska Raca, Serbia, on May 18. Hide Caption 17 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A police vehicle drives through a flooded street in Obrenovac on May 18. Hide Caption 18 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A rescuer carries an elderly woman out of her flooded house in Obrez, Serbia, on Saturday, May 17. Hide Caption 19 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Residents ride in a wagon pulled by a tractor through a flooded field in the eastern Bosnian town of Bijeljina on May 17. Hide Caption 20 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Serbian soldiers rescue a boy from a flooded house in Obrenovac on May 17. Hide Caption 21 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A Bosnian man looks through the doorway of his business in Banja Luka on May 17. Hide Caption 22 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Bosnian men ride a tractor through flooded streets of Banja Luka on May 17. Hide Caption 23 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Men paddle through the flooded streets of Obrenovac on Friday, May 16. Authorities estimate that 90% of the town has been flooded. Hide Caption 24 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A member of the Bosnian army carries a boy rescued from his home May 16 in the town of Maglaj. Hide Caption 25 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A woman tries to reach a trash container floating in the floodwaters in Obrenovac on May 16. Hide Caption 26 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – People flee their homes in Obrenovac on May 16. Hide Caption 27 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A man walks outside his home after severe floods in Obrenovac on May 16. Hide Caption 28 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Men empty buckets of water from a yard in Obrenovac on May 16. Hide Caption 29 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A child smiles from a car window on a flooded street in a suburb of Belgrade, Serbia, on Thursday, May 15. Hide Caption 30 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Homes are flooded May 15 after rivers overflowed in Sarajevo, Bosnia-Herzegovina. Hide Caption 31 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A man works to divert a stream of water from his home near Zenica, Bosnia-Herzegovina, on May 15. Hide Caption 32 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Landslide debris and floodwaters surround houses May 15 in the Bosnian village of Topcic Polje. Hide Caption 33 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – A man surveys the damage after a landslide near Sarajevo on May 15. Hide Caption 34 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – Floodwaters surround a car parked on a ramp Wednesday, May 14, in Doglodi, Bosnia-Herzegovina. Hide Caption 35 of 36 Photos: Photos: Record flooding in Balkans Record flooding in Balkans – People work to clear debris from a small stream that was clogged and causing localized flooding near their homes in Tuzla, Bosnia-Herzegovina, on Sunday, May 12. Hide Caption 36 of 36

Even though the intense rainfall subsided Monday, the disaster is far from over. CNN meteorologist Pedram Javaheri said flooding in the region will last at least another week -- and in some places, it could get worse.

The Serbian capital of Belgrade, for example, sits at the crux of the swollen Sava and Danube rivers. As water rushes downstream, the flood level in Belgrade is expected to rise through Thursday, Javaheri said.

After a day of assessments, property damage alone is estimated a $1.37 billion (1 billion euros) said Elvir Camdzic, a presidential adviser.

"When combined with the overall economic losses due to the flooding, the full scale of the damage will be measured in billions of euros," Camdzic said.

'Happy that we didn't drown'

In Serbia alone, more than 24,000 people have evacuated to escape water that is chest-high in some areas. Bosnian officials say 30,000 people are displaced in their country.

"People were in a panic, running," an evacuee told CNN affiliate N1 in Belgrade, Serbia. "I left with a kid. I was really happy that we didn't drown."

The woman's house is now flooded, and she says she has no idea where she will live.

But many Serbians wouldn't budge.

"Some people simply do not want to leave their homes," said Novica Biorac, a volunteer from a rafting club in Raska. "We are trying to convince them to leave, but it's very difficult."

Farmland hit hard

Farmers along the Danube and Sava rivers are bracing for damage assessments as the rains have stopped. The epic flooding followed an unusually dry winter that saw very little snowfall, meteorologists said.

Agriculture, especially row crop production, is still one of the most important parts of Bosnia's economy and takes up 47% of the countries landmass, according to a European Commission assessment.

Small family farms populate about half of all agricultural lands and are essential for Bosnia's food security, according to the European Union. Many of those farms are now under water, and massive landslides are a problem.

"This country is brutally destroyed by nature," said Zlatko Lagumdzija, Bosina's minister of foreign affairs. "The lanslides are absolutely destroying the country. We have registered up to 2,000," he said.

The World Food Programme said it plans to send food assistance to 150,000 people in Bosnia's most-affected areas. The organization is also sending food for 7,000 people in Serbia.

Bosnia-Herzegovina is not yet a member of the European Union, but the EU is its largest agricultural trading partners, and EU representatives say they will aid in the recovery.

"We need an assessment from the government," said Ambassador Peter Sorensen, the EU Special Representative in Bosnia. "We have ecological things with sewage, with water, with fuel and pesticides."

The EU will assist where it can, Sorensen said.

Deadly situation

The Serbian government said one of the 13 dead was someone who had already died "of natural causes," Prime Minister Aleksandar Vucic said.

One of the deceased was a rescuer, said Dragan Radovanovic, president of the Serbian branch of the Red Cross.

Authorities estimate that 90% of Obrenovac has been flooded.

Bosnian authorities say the flooded town of Maglaj received the average rainfall for two months in less than two days.

"Many cities and villages in western Serbia are completely under water," the Serbian Embassy in Washington said in a statement Sunday, describing the situation as an "unimaginable catastrophe."

Fighting the flood

Soldiers, rescue workers and volunteers rushed to stack sandbags in towns near rivers throughout Serbia.

The Sava River has already reached 6.3 meters (20.7 feet) -- a historic high, the Serbian government said. The Prime Minister said workers have erected a dam 7.3 meters (24 feet) tall in the area of Sabac.

In Kostolac, along the Danube River, workers built sandbag walls to protect a thermal power plant -- one that the energy minister called the most important power facility in Serbia. The plant produces 20% of the nation's power.

The Prime Minister thanked countries that have already come to Serbia's aid. He said he was especially grateful to members of the Russian special forces, including one member who swam 200 meters (656 feet) in cold water to save several people.

What is causing Balkans weather misery?