A statement from the town hall said that the bomb was around a metre underground.
It contains around 30 kilogrammes of explosives and an impact fuse from an original payload of 250 kilogrammes.
Police evacuated a 600-metre radius around the bomb, an area which includes businesses, schools and daycare centres as well as the train station, which will be out of service during the defusal.
A disposal team from the Brandenburg state ordnance disposal service (KMBD) hopes to have made the bomb safe by midday.
In 2013 an American 250-kilogramme bomb found on the Havel river bed in Oranienburg had to be made safe with a controlled detonation, resulting in a spectacular explosion.
7,000 people were evacuated.
Brandenburg is the German state with the largest number of unexploded World War Two bombs, and disposal teams are constantly searching for them.