Read the story. They were all little girls and there was 1 teachers aide. The teacher's aide was most likely an older/former student helping out. What would you have the children do? Wrestle a semi-automatic weapon from the guy?
read the story - there were TEACHERS inside when this whole thing started. they were sent out with the male students.
let's not get into a P$$ing contest here. this is tragic enough - but there was at least one teacher on hand at the outset.