The 39-year-old suspect reportedly spent three weeks in a psychiatric hospital in Lower Saxony and was released a day before the attack.

The police said they believed the violence, which injured 18 people during Friday’s evening rush hour, was not politically motivated.

At least 12 people were injured in a knife attack in Hamburg station on Friday evening, Germany's Bild newspaper reported, and local police confirmed they had arrested the suspected assailant. Three victims are in critical condition,