Berlin: A 500-kilo (over 1,100-pound) World War II-era bomb was detonated Monday without causing any damage in the German city of Cologne after it was discovered during construction work.
The device could not be defused because of a broken detonator so it was set off in a several-metre (foot) deep hole where it was discovered, according to city officials.
It created a "small crater and some dust" but no damage was reported in the area, the city said. However, the structural integrity of a nearby bridge still needed to be checked.
Out of precaution, a university in the area was shut down and a gymnasium housing 180 refugees was evacuated. Patients in a hospital were also moved away from the part of the building closest to the explosion.
Close to 70 years after the end of fighting, the soil in Germany remains riddled with unexploded bombs left over from the Allied campaigns of World War II. Construction crews regularly stumble upon the devices.
Authorities estimate that some 3,000 unexploded bombs remain buried in Germany's capital Berlin. In December 10,000 people were evacuated there after a 250-kilo bomb was found and then defused.