Several fans got into a crazy brawl in the stands at the Chiefs vs. Broncos game on Sunday ... and things turned so violent, TMZ Sports has learned one of the guys involved was actually charged with assault.
The incident took place at some point during Kansas City's 16-14 win over Denver at Arrowhead Stadium.
According to video shot by a bystander, it all appeared to begin when a Patrick Surtain II supporter started throwing hands at a neighboring fan.
You can see in the clip that security attempted to break things up .