Eighteen children were among those injured after a man drove his car into a crowd at a carnival in the German town of Volkmarsen.
A total of 35 people are still in hospital following the incident, while seventeen others have been treated and released.
Police are still looking for a motive behind the 29-year-old suspect’s actions, but they believe it was a deliberate attack.
According to Bild newspaper, the man was from the local area and was also injured.
He is reportedly in hospital with serious head injuries, and police have not yet been able to question him.
The crash in the town of about 7,000 near Kassel, north of Frankfurt, came at the height of Germany’s carnival season, with the biggest parades in Cologne, Duesseldorf and Mainz.
All other parades in the central state of Hesse were ended on Monday as a precaution.
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A spokesman for Frankfurt prosecutors, Alexander Badle, said in a statement that “about 30 people” were injured, including children. They were taken to surrounding hospitals, some with life-threatening injuries.
The suspect was also injured, said Mr Badle.
“The investigation, especially into the circumstances of the crime, continues,” he said. “In particular, no information can yet be provided about a motive. The investigation is exploring all avenues.”
“This is a terrible act committed against people who simply wanted to celebrate Carnival,” said Peter Beuth, the interior minister for the state of Hesse.
He declined to comment on reports that a second person had been detained.
Chancellor Angela Merkel sent her condolences to those injured in the crash, wishing them a speedy and full recovery. She also thanked police and medical personnel involved.
Emergency responders set up a makeshift clinic in a town pharmacy to treat casualties with minor injuries, the regional Frankfurter Rundschau newspaper reported.
Witnesses said the car drove around a barrier blocking off traffic from the parade, according to the paper.
Video from the scene showed a silver Mercedes with local licence plates on a pavement, its front windscreen badly smashed and bonnet dented, and its hazard lights blinking, while emergency crews walked by.