Nieuwegein – The organization of the Solid Grooves festival says it is shocked by the deadly stabbing incident that took place on the Amsterdam festival site on Sunday evening. A 21-year-old man from Diemen was killed. Two other visitors, a 22-year-old man from Nieuwegein and a 24-year-old man from Amsterdam, were injured. They are still in the hospital, but their life is not in danger.