Well i am talking in terms of soccer refereeing and we get regular training but even with that training it takes a certain personality to be a ref.
Most years about 50+ refs take up the whistle but only 5 may stick it more than a year.
handling tense situations us key to that. Staying calm when all around is losing their head. Being firm and clear with what you are saying, allowing people time to calm and realise what they are saying and using common sense.
Looking for help from someone more reasonable etc. and giving plenty of warning that you will walk if it continues.
Strong body language and strict instruction as well as engagement are vital.