Authorities on Sunday defused a World War II bomb weighing 500 kilograms (1,100 pounds) in central Frankfurt, Germany's financial capital.

Efforts to make the 500-kilogram (1,100-pound) American-origin bomb safe disrupted parts of the city, officials said.

Around 16,500 residents were told to leave their homes by early Sunday morning, while some 25 coma, stroke and dementia patients were transferred from nearby nursing homes and hospitals to other facilities a day earlier.

Read more: Who disarms Germany's WWII bombs?

Authorities created an evacuation zone around the area, which included parts of the European Central Bank (ECB) and much of the city's east end on both sides of the Main River.

Frankfurt Zoo, which lies slightly north of the zone, remained closed on Sunday. The animals were not expected to be moved.

By early afternoon, authorities had cleared the bomb. "It went smoothly," said a spokesman for the ordnance clearance service.

Read more: WWII bomb self-detonates in German field, leaves crater

Frankfurt's fire department is well-versed in bomb disposal operations. In September 2017, 65,000 residents had to be evacuated so that a huge British "blockbuster” bomb weighing 1,600 kilograms could be removed.

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