The entire FedExField staff is aggressively opposed to this kind of behavior, and will do everything they can to stop it once they learn of it. The attendants are all versed on how to respond to fights, or any behavior that dilutes another fan's enjoyment of the game.
A text to SKINS at 69050 followed by a section and row will bring Stadium security quickly - usually within a minute or two. You can also call 301 276-6100, but it's difficult to be heard with the crowd noise. Problem fans will be escorted out of the Stadium. If more serious charges are warranted, they'll be placed in a holding cell until after the game, and then process for arrest by the PG County police after the game.
This text info - SKINS 69050 - is displayed in all four corners of the stadium between the two suite levels. It can be seen from almost anywhere in the bowl.
EDITED to remove my POV (Because Mark is THE MAN and said everything that needed to be said!)