Charge them with "accessory to murder". Who knows what was going on behind the scene during their active shooter training? Maybe this was the plan all along. Make them sweat bullets, or anything else. BTW, I don't think there should ever be active shooter training in any school where children are in attendance. This seems to be the fountainhead of many mass school shootings. Have some random building and use that for training. They don't need the schools for that.