The discovery of a World War II bomb in Cologne, Germany, on Tuesday evening prompted authorities to request more than 3,000 people to leave their homes.

The explosive was uncovered in the Sülz district of the west German city.

"World War II bomb found in Sülz," the official account of the city of Cologne posted on X. "During construction work this Tuesday afternoon, an unexploded bomb from World War II was found in the area of ​​Luxemburger Straße/Greinstraße in Sülz, which must be defused today."

The roughly 500-kilo (1,100-pound) bomb had to be defused immediately, the city authorities said, with German media reports suggesting it was an American bomb.

This meant the evacuation of a high-rise residential building, the Uni-Center, with almost 1,000 apartments. It is the fifth tallest in Cologne, and one of Europe's largest residential buildings, standing at 134 meters high, and was opened in 1973.

The danger zone has a radius of some 350 meters (1150 feet).

The unexploded bomb was later safely defused, and evacuated residents were allowed back into their houses.

Unexploded bombs frequent occurrence in Germany

In October of this year, Cologne city authorities conducted a controlled detonation of a large World War II bomb produced in the United States. The controlled explosion was carried out after failing in initial attempts to defuse the 1-ton bomb. The city said it was the most complex bomb disposal operation since 1945 as several hospitals were nearby.

It is not unusual to find unexploded ordinances from World War II in Germany, and in particular in Cologne, the country's fourth largest city after Berlin, Hamburg and Munich.

Cologne was a crucial industrial focal point for Nazi Germany during World War II and it was also one of the more viable targets for bombing raids launched from the British mainland.

Situated on the western edges of Germany, very close to the French, Dutch and Belgian borders, Cologne was the target of the first of the bombing raids conducted by Britain's Royal Airforce in the summer of 1942. The bombardment flattened a large portion of Cologne's city center, while missing its renowned cathedral on the banks of the Rhine almost entirely.

Edited by: Roshni Majumdar