We had chemical spills and a fire..both times making us stand outside. It was so hott that a few kids passed out.
I didn't go to school the day we had a bomb scare..it was Columbine's anniversary and I refused to go to school because I had offended too many people in my HS career.
I think we had a mild explosion in the chemistry lab once. teacher's fault, he forgot to place some chemicals under the hood and the fumes pooled and had a reaction. something like that.