Freezing when something like that is happening is not an option, ever.
Slow down here. Until you are in a situation you don't know how you will react. Several years ago we had a school assembly in which a fight broke out. There were about 15 teachers in the Auditorium when it happened. It happened so fast and was so violent that myself and another teacher were the only ones to react. The difference between us and them was that we both had Martial Arts training wee able to see the events before they unfolded.
Two entirely different situations.