No matter what the laws, this teacher would not have been armed, nor would she have shot this maniac.
My fervent belief (acknowledging that I dont know any more about the situation "on the ground" than ANY of you do), is thus....
I would imagine that any and all older teenagers (NOTE I did not say "ADULT"--that was ordered to leave, probably ran as fast as their legs could take them to notify their fathers, mothers, or find anyone who had a phone!
Prayers up for ALL those effected by this horrendous act