A man was critically injured in a stabbing at a public May Day celebration in Inden. Another man suffered serious injuries, the public prosecutor said on Tuesday in Aachen. The argument happened in the vicinity of the May Festival in a marquee with around 500 revelers. There was a private dispute between people on the forecourt. When a group of bystanders later left the marquee, they were suddenly attacked. Several people were injured in this altercation. The critically injured man had to be operated on. Investigations to identify those involved are ongoing.