Muenster (CNN)A man who drove a van into a crowd of people killing two and injuring 20 Saturday in Germany acted alone, according to police.
Muenster van attack driver acted alone, police say
However, investigators told a news conference it's too early to say what motivated the driver, who has not been named, to plow his vehicle into a restaurant's open terrace in the western German city of Muenster before shooting and killing himself.
German Interior Minister Horst Seehofer at the conference Sunday said the man could have been mentally ill, though he told reporters authorities are "investigating in all directions."
The attack happened about 3:30 p.m. in the old part of Muenster, an area popular on weekends. It was a warm sunny afternoon, one of the first nice days of spring, and many people were outside enjoying the good weather when the crash occurred, said Julian Reichelt, the editor of the popular German tabloid BILD.
The timing of Saturday's incident prompted speculation about the driver's motives. It occurred on the one-year anniversary of an attack in Stockholm, Sweden, in which a man drove stolen beer truck into a crowd of pedestrians, killing five. That suspect later admitted to carrying out a "terrorist crime."
Herbert Reul, the minister for internal affairs in the state of North Rhine-Westphalia -- where Muenster is located -- said there was no known connection to radical Islam in Saturday's crash, but noted that investigators are still combing through the man's background.
The driver had a history of petty crime, Muenster police spokesman Rolf Werenbeck-Ueding told CNN.
Police had said they are investigating witness reports of people fleeing out of the van after the attack. Spokesman Jochan Laschki said the driver had no accomplices, and the investigation is ongoing.
Muenster, with about 300,000 people, is home to numerous universities and has a student population of about 58,000, the city government says. The city calls itself the cycling capital of Germany and says about 100,000 residents use a bike daily.