Six people have been arrested over a suspected plot to launch a knife attack at the Berlin half-marathon.
In a joint statement, prosecutors and police said: "There were isolated indications that those arrested, aged between 18 and 21 years, were participating in the preparation of a crime in connection with this event."
Local media said the main suspect, who has not been identified, had been under observation for two weeks and had prepared two knives to use in the potential race attack.
The German newspaper Die Welt reported the main suspect in the plot knew Anis Amri, the Tunisian who killed 12 people and injured dozens after driving a van into crowds at the Berlin Christmas market in December 2016.
The newspaper reported an apartment searched in the aftermath of the Christmas market attack was again raided before Sunday's half-marathon.
German agencies say the race was guarded by around 630 police officers.