I probably don't have the full story, but the guy on KC 980am said that the shooter went to the school so that one specific teacher could get dealt with. The teacher was tipped off early by someone and just left. Then another student confronted the shooter as he entered the building. Shooter hurt confronter then killed himself.
So, teacher gets tip and just leaves. Cops? nope. Notify principal or onsite staff? nope. Just lets another student handle that noise. WTF?