Protesters demonstrated against the "violation of parents’ rights in education" of their children.150 parents were attacked by about 600 left-wing radicals who threw eggs, fireworks and bottles into the crowd of demonstrators. A 15 year-old girl had to be taken to the hospital. Police intervened.
Sources:
http://www.n24.de/n24/Nachrichten/Politik/d/6043836/demo-zur-hamburger-sexualkunde-eskaliert.html http://www.besorgte-eltern.net/index.html