Police have been checking to make sure the evacuation area is deserted since 8am, according to the Rostock police.
The 250 kg bomb had been found on Monday during construction work next to a busy street in the centre of Rostock, a city on the Baltic Sea in Mecklenburg-Western Pomerania.
The device is an American air bomb with two detonators, according to police spokesperson Michael Ebert.
According to a city spokesman, schools and kindergartens remain closed within a thousand meters of the site.
The tram and bus traffic in this area has been stopped so that the bomb disposal can take place. The city administration provided emergency accommodation in the Rostock city hall.
“We also go from house to house and check whether everyone is really leaving the evacuation area,” police spokeswoman Yvonne Hanske told the Ostsee Zeitung.
During the Second World War, 21 air attacks were carried out on Rostock. From June 1940 to April 1943, they were led by the British Royal Air Force and from July 1943 to August 1944 by the US Air Force.
Throughout Germany, World War II bomb finds – resulting city evacuations during their detonation – are commonplace.
In February, over 4,000 residents in Essen were evacuated when an American bomb was found during construction work.
Just a couple of weeks later, a 250 kilogram bomb was found in the centre of Nuremberg during construction work, leading to the evacuation of 8,000 residents.