Ok so:
-There was a nuclear&biological world war.
-During the war Supersoldiers were made
-Supersoldiers have children who tend to also become supersoldiers
-Regular citizens also sometimes have supersoldier children, so every child is monitored
-Solution to this supersoldier epidemic is to kill all children who exhibit any symptoms, while dressed as rabbits
-Supersoldiers don't kill willingly but are triggered automatically by an opponents malice towards the spike-user
-All this is known by all adults, but not by children
-Teacher's reaction to seeing a child exhibiting full super-powers killing one of the rabbit dressed killers (and then provoked into killing a nearby student) is to scream "MONSTER! KILL IT!"
Teacher is exhibiting standard horror story character intelligence, she doesn't seem suicidal, what does she think is going to happen next? The students are going to rush the super in a human wave? Granted they do start throwing cans and erasers at the killing machine instead of running away so maybe that world war involved spraying with crazy suicide juice.