Three people died and about 20 were injured in the western German city of Muenster after a van drove into a crowd Saturday afternoon.
Police urged people to avoid the area near the Kiepenkerl, a popular pub in the downtown area.
One day after a van killed multiple pedestrians in Muenster, German police appear to have thwarted a series of planned knife attacks on Sunday's Berlin half-marathon race.
"The perpetrator killed himself in the vehicle", Bode added.
The Frankfurter Allgemeine Zeitung reported in its online edition that the perpetrator was Jens R., 48, who resided some 2 km (1.2 miles) from the crime scene. The report said the man had wanted to revenge after the death of his accomplice Amri.
Despite investigators' increased certainty about the perpetrator's mental health, "it will take a few more hours and days" before the case is fully cleared up, North Rhine-Westphalia state interior minister Herbert Reul said on Sunday.
Die Welt reported that the main suspect, who was not identified, had prepared two knives to use in the attack.
The driver committed suicide inside the van, police said. Authorities are still clueless about his motives and said they're investigating in all possible directions. "That is our current task", Bode said. "And the police arrived and everyone was sent out", he said.
Martin Wiech, who said he had studied in Muenster, told Der Spiegel he had driven to Muenster to go shopping and was now unable to return to his auto.
Witnesses said people ran away screaming from the city square after the crash.
A court last month sentenced a 26-year-old Palestinian asylum seeker to life in prison for killing one and wounding six others with a knife in a Hamburg supermarket out of a "jihadist" motive last July.
Berlin's top security official, Andreas Geisel, had said earlier that the capital of 3.5 million people would need to review its precautions for the half marathon following the Muenster attack in which two people were killed.
The newspaper said the four men were linked to Anis Amri, a Tunisian man with Islamist militant ties who killed 12 people in an attack in Berlin in December 2016 when he hijacked a truck and drove it into a crowded marketplace.
Chancellor Angela Merkel said in a statement she was "deeply shaken".
The presidents of Russian Federation and France, Vladimir Putin and Emmanuel Macron, each sent their condolences. "France shares in Germany's suffering".