I worked a lot of MI state fairs as EMS and we were really tight with MSP and the contract security there. We never had any incidents of this type but there always was "gang night" which was either the first or second Saturday night and all the gangbangers would come hang out and usually there would be some rap or R&B concert. There were always fights and sometimes huge ones. Like ringo said MSP came out in force for the fairs. Each post would send a detail and the state would put them up in a hotel (the parties were awesome but those stories are not for the internet
) and to top it off there was a pvt security force of at least 100. arrests were common, in recent years at least 1 person got tazed each week but still they came and still they fought. I practically lived there when I worked so my gun was with me.
So my answer to the scenario is. Sorry best bet is to walk softly and carry a big gun. Threaten my life and you get the gun otherwise walk softly and avoid the mob.