Kids are disgrace
I feel these kids are a disgrace, there's a fine line between prank and destruction. They grand-slammed over it. Those select kids that did this, should not get any of the joys or rewards of graduation, such as senior celebration and walking at graduation.
Instead I feel they should each stand up alone and apologize to everyone at the graduation ceremony and sit there as their classmates walk and get diplomas, also slap them with 200 hours of community service and I think you'll have your senior "prank" or destruction, whichever you prefer to label it, solved.