BELGRADE, Serbia-Montenegro (AP) – Floods threatened cities and fertile lands across Serbia as record water levels on one of Europe’s longest rivers surged downstream towards neighbouring Romania and Bulgaria on Monday.

In Serbia, emergency crews and volunteers struggled to keep embankments and sand barriers from giving way as the River Danube’s water levels started receding. Meanwhile, the Tisa River, which flows from Hungary in the north, started rising dramatically.

Thousands of civil protection workers and soldiers in Romania and Bulgaria were working to bolster dikes and build new ones. The peak of the Danube floodwaters was expected to reach the two Balkan countries in the next few days.

Spring melting of snow together with heavy rains has led to floods throughout southeastern Europe in the past few weeks.

The Danube – Europe’s second-longest river – was flowing at a record 15,800 cubic meters (558,000 cubic feet) per second, or double the average for this time of year, Romania’s Environment and Water Management Ministry said.

The Danube’s water level at Bulgaria’s northwestern port city of Vidin rose by 5 centimeters (2 inches) in the last 24 hours, reaching a record 9.7 meters (31.6 feet) on Monday morning, the Civil Defense Agency said.

More than 3,000 residents left on their own or were evacuated by the police from the southern Romanian villages of Rast and Negoi after a dike collapsed Sunday, flooding the communities.