Two people were killed and some 20 injured after a van drove into a crowd in the western German city of Muenster on April 7, German authorities said.
Police spokesman Andreas Bode told reporters that the driver of the vehicle killed himself after the crash. He said the driver's identity was not yet known and that it was too early to speculate about his motive.
Bode said six of the injured were in severe condition.
"The perpetrator drove into several cafe and restaurant terraces in a major square in the center of Muenster," a police spokeswoman said.
State Interior Minister Herbert Reuel said investigators believe the perpetrator is a German citizen and that the incident did not appear to be related to international terrorism.
"Nothing indicates at the moment that there's an Islamist background," Reuel said.
Reuel also said that two people had been killed in the crash, revising an earlier police figure of three.
A leading German newspaper reported that the driver is believed to be a 48-year-old German man who had psychological issues.
The Sueddeutsche Zeitung paper also says the suspect's apartment was being searched for possible explosives.
Police said a suspicious object was found in the van and they're still examining it to see if it is dangerous.
Earlier, the online edition of Der Spiegel magazine reported that German authorities were "assuming" the incident was an attack, though there was no immediate official confirmation.
Ulrike Demmer, a spokeswoman for German Chancellor Angela Merkel, said "our thoughts are with the victims and their families."
She said in a tweet that the crash was "terrible news."