notintheface
GOLD
Certified to deal with that behavior? Not in my class.
Your class didn't cover the material, then. Immediately show up on the scene, whistling multiple times, multiple verbal warnings including telling the kid in question that he/she will cause their team to forfeit if they don't stop, coaches entering the field will reinforce this, physical restraint starts with one hand to interrupt aggression, more verbal warnings, then coaches may pull their player away.
In the heat of the moment it may be different but coaches should show up on scene to separate their player and it is the coaches responsibility to make sure that player leaves the field; hand them off to parents and tell them to take him/her home.