Is it possible that some of those poor helpless children might have been saved if some people inside the school had weapons with which to protect the kids from lunatics? There are some reports that the principal and maybe others tried to stop the derranged kid but were shot dead. If these brave people had been armed, pehaps they could have ended whatever torment the shooter was experiencing before he took so many innocent lives.
Even lunatics who commit this kind of atrocity realize that the jig is up when deadly force arrives, whether that be in the form of the police after everyone is already dead, or in the form of one or more sane, law abiding citizens trained by the NRA in self defense. Whether or not it would have made a difference in this particular case, removing the freedom of a peaceful, mentally competent person to defend themselves as a knee jerk reaction to tragedy would, as removing freedom almost always does, make the situation worse.
Now everybody send me as many negreps as you can.