The World War II bomb found during construction work in Friedberg is to be defused on Thursday evening.
Houses within 250 meters of the site were evacuated, the police said.
With loudspeaker announcements and door-to-door controls, the emergency services urged residents to leave their homes.
Emergency shelter was set up in the Friedberg town hall.
Friedberg - Rescue services, ordnance clearance, fire brigade, police and employees of the city and the district of Wetterau are in action, the police had previously informed.
The 75-kilogram bomb was discovered on Thursday afternoon in the Fauerbach district.
A World War II bomb had already been successfully defused in the East Hessian Friedewald by noon.
dpa