The fights, which often take place on concrete, involve severe head injuries, biting and eye gouging.
According to martial arts law, it is prohibited to organize matches where punches and kicks to the head occur - despite this, the King of Streets organization makes money by streaming its fights to paying viewers.
"Maybe I'm using the word naive, but we haven't looked at this problem as we should over the years," local police chief Max Olsson tells UG.
But in the past year, the police have shifted their focus to target the organization, according to Olsson.
It's not just this part of their lives that is criminal.
