The clashes took place in the Stuttgart fan zone, involving a 25-year-old man who injured three others.

The German police did not want to disclose the nationality of the attacker, who, according to Bild, is believed to be Turkish.

A witness present at the scene recalled the moments of panic.

"Everyone was running for the exit. Some people were kicked. Fortunately, nobody fell, otherwise it could have been worse," he said.

It's still being investigated how the weapon got past fan zone security in Stuttgart.