Historic flooding in the Balkans sent tens of thousands of people scrambling to higher ground on Sunday and sparked concerns that landmines from the Bosnian war could surface in mudslides, putting rescuers' lives at risk.
"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."
"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.
In Serbia, the severe flooding has prompted the evacuation of at least 24,300 people.
Dragan Radovanovic, president of the Serbian branch of the Red Cross, said the number of people affected by the high water is actually much larger. Many people stayed in the houses or apartments, one rescuer told Reuters.
"Some people simply do not want to leave their homes," Novica Biorac, a volunteer from a rafting club in Raska, said. "We are trying to convince them to leave, but it's very difficult."
Water in some places was chest high as rescuers shouted up to people in buildings who are stranded.
One woman lowered a bucket, and a worker put a loaf of bread in it.
"Thank you, please come back again and also let us know what the time is. I have a clock but don't have any batteries," she shouted to the rescue team, according to Reuters.
Twelve bodies have been recovered in Obrenovac, about 35 kilometers (22.7 miles) from the capital of Belgrade, the Serbian government said Sunday evening. One of the 12 was someone who had already died "of natural causes," Serbian Prime Minister Aleksandar Vucic said, according to a government statement. Authorities estimate that 90% of the town has been flooded.
At least 13 people are dead in Bosnia and Herzegovina, Deputy Minister of Security Samir Agic said.
The toll is likely to go even higher, officials cautioned.
MORE at CNN.com