COLOGNE, Germany (AP) — More than 20,000 residents were being evacuated from part of Cologne's city center on Wednesday as specialists prepared to defuse three unexploded U.S. bombs from World War II that were unearthed earlier this week.

Even 80 years after the end of the war, unexploded bombs dropped during wartime air raids are frequently found in Germany.

Disposing of them sometimes entails large-scale precautionary evacuations such as the one on Wednesday, though the location this time was unusually prominent and this is Cologne's biggest evacuation since 1945. There have been bigger evacuations in other cities.

Authorities on Wednesday morning started evacuating about 20,500 residents from an area within a 1,000-meter (3,280-foot) radius of the bombs, which were discovered on Monday during preparatory work for road construction. They were found in the Deutz district, just across the Rhine River from Cologne's historic center.

As well as homes, the area includes 58 hotels, nine schools, several museums and office buildings and the Messe/Deutz train station. It also includes three bridges across the Rhine — among them the heavily used Hohenzollern railway bridge, which leads into Cologne's central station and is being shut during the defusal work itself. Shipping on the Rhine will also be suspended.

The plan is for the bombs to be defused during the course of the day. When exactly that happens depends on how long it takes for authorities to be sure that everyone is out of the evacuation zone.