FRANKFURT (AP) -- Thousands of people in the southern German city of Augsburg have left Christmas presents and decorations behind, forced to evacuate while authorities disarm a large World War II aerial bomb.

The bomb was uncovered last week during construction work in the city's historic central district.  Police say Christmas Day is the best time to defuse it because there is less traffic and it is more likely people can stay with relatives.

Police rang doorbells and used vans with loudspeakers to urge procrastinators to leave ahead of a 10 a.m. deadline. Traffic into the evacuation zone was halted from 8 a.m. local time.

Some 32,000 homes with 54,000 residents are in the evacuation zone. Christmas morning services at the medieval cathedral with its famed boys' choir were moved to another church.

Police aren't making any promises about how long it will take to disarm the bomb. Schools and sports facilities have been opened as shelters, but police said they were not full and many people had already left for relatives' homes Christmas Eve. About 200 people came to the town's exhibition center and 100 to the WWK Arena sports stadium. Public transportation was free of charge for the evacuation.

Finding World War II bombs is not unusual in Germany. Much of Augsburg's historic center was destroyed on Feb. 25-26, 1944, when hundreds of British and U.S. bombers attacked the city.