A soccer game between Germany and Netherlands which German Chancellor Angel Merkel was due to attend in Hanover was called off two hours before its scheduled start on Tuesday over fears of a planned bombing.
The match was due to have been held four days after the deadly attacks in Paris on Friday, when suicide bombers targeted the soccer stadium where Germany was playing France.
"We had received specific indications that an attack with explosives was planned," Hanover Police President Volker Kluwe told NDR state broadcaster. "We took them seriously and that is why we took the measures."
"We do not know if these people, who had planned something for the stadium, had planned something else so we try to have a presence throughout the city," he said
Police vans with loudspeakers ordered fans to leave the Hanover stadium and heavily armed officers positioned themselves outside the arena.
Police also evacuated Hanover's TUI multi-purpose arena where a concert was about to start while officers checked cars and pedestrians in the city centre and sniffer dogs were deployed.
A train on its way to southern Germany was also stopped at Hanover station with police removing a suspicious package before giving the all-clear for the train to continue its journey.
There were no arrests made and no explosives were found, Lower Saxony Interior Minister Boris Pistorius said.
Interior Minister Thomas de Maiziere said the threat was credible and cancelling the game was the right thing to do, but did not provide any details.
"I understand the question but I will not answer it," he told a hastily convened news conference when asked what had forced the decision. He said divulging details could undermine security at other events.
"I am asking for an advance of trust from the German people. We will have such cases in the future, maybe not Hanover but somewhere else," he said.
After Friday's attacks in Paris security measures in Hanover had been tight. In a show of solidarity, Merkel was set to attend the soccer match with Vice Chancellor Sigmar Gabriel and several government ministers.
Interim German Football Association President Reinhard Rauball said he called up the team in the bus some five kilometres (3 miles) from the stadium, telling them the game was cancelled.
Both the German and the Dutch teams were then rushed to a secure undisclosed location before the hosts left individually for their homes and the visitors for the airport.
"That we would go through this twice in four days is not something I could imagine," Rauball, visibly shaken, told reporters. "It is a sad day for Germany and a sad day for German football."
Two Dutch government ministers who were due to attend the match - Defence Minister Jeanine Hennes and Health and Sport Minister Edith Schippers - were also returning home.
World champions Germany had not initially wanted the game to go ahead after having played in Paris on Friday as a wave of attacks hit the city, killing 129 people.
The contingent of 80 Germans, including players, coaches and staff, spent the night holed up in the changing rooms of the Stade de France stadium, before heading for the airport on Saturday morning.
The players, coaches and the national football association decided to go ahead with the Hanover game in a gesture of solidarity with France.