Yes, it is sad... if that principle had a gun, if the custodian did, or if there was an armed guard the shooter may not have even tried it.
BUT, these two incidents are very very different... in Newton, the shooter went there for thrill of killing knowing he would not be shot at. In this incident, the shooter was after one individual because of some type of arguemnt. IN the 1970's that would hav emeant a fight after school... sadly today that means one of them shoots at the other.
Both are sad commentaries on the state of society today.