Three people were severely injured in a knife attack on a German express train on Saturday.
The passengers were attacked on a high-speed train travelling between Nuremberg and Regensburg in southern Germany.
A 27-year-old man was arrested, and there was no wider threat to the public, police said. No other details were given about the suspect.
Horst Seehofer, Germany’s Interior Minister, said it was too early to establish a motive for what he described as a “terrible knife attack”.
He said staff on the train had intervened to prevent the situation from deteriorating further.
“I hope that the injured people and those who witnessed what happened will make a quick and full recovery,” Mr Seehofer said.
“I thank everyone, especially the police and train personnel, for their brave actions, which prevented things from getting even worse.”
Red Cross workers who arrived at the scene helped to transport three severely injured people for treatment, the charity said. Its staff were looking after passengers.
The railway line remained blocked until the evening, with long-distance trains taken on a diversion. The train in question was heading for Hamburg in northern Germany.