Schools, childcare centers and government facilities closed and various bomb specialists started to work in German city of Cologne on Wednesday after investigators found a 200 kg WWII bomb in the city.
Around 20,000 city residents have been faced with mass evacuation after investigators found the bomb near Rhine River.
Government officials say that during the deactivation process the river and the air space of Cologne will remain closed due to safety concerns.
A spokesman from the munitions disposal squad Wolfgang Wolf said that the seven-decade-old bomb has the potential to create a large shockwave.
"We have here [explosive] TNT that generates shock waves over a wide distance that can rip off roofs, windows, doors and so on," Wolf added.
Germany has been faced with unexploded WWII materials every year. Recently, a 250kg bomb was found under a school building in Hannover which caused the evacuation of 31,000 residents.
In 2014, a 250-kilogram bomb from WWII under the Brandenburg state parliament was also deactivated. In 2011, government officials evacuated 45,000 people in city of Koblenz due to the discovery of another WWII bomb.