Yeah, the cops sucked at making sure everything went down correctly. but hindsigh is 20/20
Assuming that only a few of the persons (if that many) were armed, the "friendly fire" injuries would be minimal.
If EVERYONE was armed, then the likely hood that the attack would happen would most likely decrease, and even if it did still occur, then once the gunman was down he wouldn't've been able to shoot-to-kill random people.
It seems reasonable that once the gunman was stopped then the shooting would stop. And more likely than not, stray bullets from good samaritans would cause fewer fatal injuries than a man aiming to kill everyone he can.
...as it stands now, weapons are ok for legal adults on the streets, weapons are available to ALL criminals anywhere...why not allow students to carry is they so choose?