Harassed by a hostile racist in front of Stephansdom. What can I do?

Hi all, my family and I were visiting Vienna today when we were verbally attacked by a man selling concert tickets in front of St. Stephan's Cathedral. He was wearing the red and white outfit that many other concert ticket sellers wear near that area (red vest and white blouse I believe).

He handed my sister a flyer but my mother had her give it back and politely said we don't have time to visit the concert. He suddenly became very angry and frustrated, calling my mother "fake" and muttering other words. I happened to catch him saying that as she walked away and I went up to him, asking "What did you just say?" He then proceeded to tell me, "You are fake. You are all fake. You Chinese people. Never come here again. Never come here."

I walked away but later went back to ask him for his name, telling him that I wanted to buy a ticket, but he refused to answer, saying, "Why? Why?" We started to leave again but he followed us 100 meters and pointed the middle finger at us, yelling at my sister, "I am going to put this finger in your vag," before we finally escaped from him.

My family and I are very shocked at the way this man treated and threatened us, but I know he does not represent the rest of Vienna. We found that Viennese people were very friendly to us.

My question is there any way I could report this man and prevent him from harassing any other tourists? I really do not want others to experience what we faced today, but I do not know where he works or what his name is.

If you have any suggestions, I would very much appreciate it. Thank you.

TLDR: Was harassed by a man selling concert tickets in front of St. Stephan's Cathedral. I would like to report him but do not know how.