Teacher is involved; there is some nuance in Virginia law that requires it. That said, there are dozens of lawsuits stemming from this incident. The only ones who are certain to come out ahead are the lawyers.
And to extend this to Drum Corps- if, heaven forbid, a member is seriously injured by a prop, I can foresee multiple lawsuits. The member, the other members who were imperiled but not injured, the members who were traumatized by witnessing the accident, etc