Some 50,000 people have been evacuated from their homes in Hannover while experts defuse five suspected Second World War aerial bombs.
The operation, the second largest to be carried out in Germany, comes after two bombs were found at a construction site in the city and three others were found nearby.
Authorities - who had delivered leaflets door-to-door and translated in German, Turkish, Polish, English and Russian - said they expect everyone to return to their homes on Sunday evening.
Evacuated residents were told to turn off their gas supply and electrical appliances, taking with any medical supplies, before the 9am deadline.
Museums in the city are open for free and the senior citizens' agency organised an afternoon Scrabble and card-playing gathering so evacuated residents have somewhere to go.
Thousands of soup portions were also being prepared.
Hannover was bombed heavily by Allied planes during the war and such finds are common.
On one night alone - 9 October 1943 - Allied forces dropped over 261,000 bombs killing 1,245 people and leaving 250,000 homeless.