DO NOT;
-Tell them to calm down
-Immediately confront them
-Yell at them
-Advice them that being angry isnt good on the spot

That will only make them more angry and worse, you have the risk of making them dislike you. Do not do this when they are angry. They will NOT agree nor listen to you when they are steamed up like that.

DO;
-On the sidelines, tell them that their anger is valid
-Be there for them and listen to them
-Wait for them to calm down then comfort them
-Talk with them and discuss/advice AFTER they calm down

Not only will there be a way less chance of them lashing out at you, but they will be more able to listen to you.

Anger is a pretty strong emotion that can blind people. Almost everyone CANNOT think straight when they are mad. Don’t add to the fire.

Wait for them to calm down without confronting them or screaming “ CALM DOWN ” at them.