"" I've read in some tactics rags and articles that if faced with a mob, gang, or any sizable group, to try to find the leader and take them out first ""
I'm not convinced the Milwaukee incident had a single leader. It was likely more of a common target to focus on with individuals carrying out their own operations than one person directing the show.
Some time back, there was a news report talking about mid east terror cells that ascribe to a common goal but are independent in operation. I'd think the fair incident is similar. In this case you have to go after the person attacking you rather than looking farther.