This article is completely misleading.... Look at the chart from the article itself:
The blue line represents "gun related incidents at schools". These seem to average, roughly, 20 a year, with a high of (say maybe) 38.
The red line represents victims. The low is 25 (1985?) while the high is 140 (2003?). The last "recent low" we had was 2005 with about 70 victims, whie we are currently running at over 120 victims. The's the third highest amount of victims since 1976.
The amount of incidents remains steady, but the amount of victims is clearly on the rise.