What should i do if this happens again?

this is a serious situation ok i went on a filed trip to a dinner/arcade had fun but when we got on the bus to go to Jackson park this teen named Brandon well at first he stared cuss and some other boy did to but then the problem got worse&worse he then threaten to kill tat boy and then one of my teachers took the other boy out to the visitor information center to keep him from making Brandon madder but that did not help either so he tried to break the window of the bus to walk out side and tried to run out the bus door to get him he could have hurted or kill us other students too i mean i stared to cry and wanted my Nana Mommy / Papa luckily my teacher garbed him tight and putted him on the floor to prevent him from moving 1 inch i still was scared to death that's when on of my other teachers took all of us other students out side to the visitor information center too but then the police came to help out the problem then the ambulance came to take him away they go get him i saw him strapped up in a straight jacket and then they putted him in the ambulance and in about 6 minutes they drove off to the hospital hopefully he will stay there entill the entire school year is over i bet a game that he is going to get expelled from my school so any way what should i do if another student start doing this again please help me he scared the heck outta of me this is truth i repeat this is all truth i am 14 that teen i was talking about is 15