Only a couple do that I know of, dealing with multiple attackers,
who all attack at the same time, is more often taught. Do you actually think that they will stand around and let you take one of them out, perhaps then they will all come at you one by one as they do in the films?
I have done a lot of riot training, even had to use it but we don't focus on the 'leader' there's snatch squads for that, obviously you won't have that luxury so focussing on the 'leaders', once you know who they are is something you are unlikely to be able to do.
Quite a few years ago two soldiers in Northern Ireland were beaten to death by a mob, nothing helped.
BBC - History - Troubles - Army corporals killed at IRA funeral