Eighteen of those hurt in Monday's incident are children. In total 35 people remain in hospital.

Frankfurt's general prosecutor's office announced that the victims were aged between two and 85 years old.

A 29-year-old German citizen was arrested on suspicion of attempted homicide in the town of Volkmarsen.

The motive is unclear. Planned carnival events are to be held in Hesse state, where the town is located, on Tuesday.

A statement by Hesse police said there were no "concrete indications" the risk had increased at these processions, although police warn security arrangements could be reviewed.

Police have also arrested a second person for allegedly filming the incident, the statement said.

Authorities cautioned against sharing images of the incident after one picture circulated online claimed to show the driver being arrested, but in fact showed a different person.