Authorities in Cologne closed off a large section of the city center Wednesday, evacuating homes and businesses and shuttering tourist spots, as experts worked to defuse three unexploded mega-bombs from World War II.

Up to 20,000 people have been evacuated in the German city of cologne after three unexploded WWII bombs were discovered on Wednesday.

Authorities in Cologne closed off a large section of the city center Wednesday, evacuating homes and businesses and shuttering tourist spots, as experts worked to defuse three…