Students at Franklin Regional High School in Murrysville, Pa., have been buying tickets for the prom, griping about make-up days because of snow cancellations this winter, studying for tests and, in general, behaving like most teenagers.

Until morning on May 9. For a few hours then, the school near Pittsburgh was a scene of bloody chaos. A 16-year-old boy stalked the halls, brandishing two knives. Before he could be subdued, he had stabbed and slashed several fellow students and one adult. Some were injured badly.

What happened? Police began questioning the boy Wednesday afternoon. It probably will be days before they uncover his motive.

The Franklin school district is not unlike many in this area, though it is in a relatively prosperous area. Students there do well in comparison to many other districts in Pennsylvania. Murrysville itself has about 19,000 resident, and the school system serves two smaller towns.

That may be the most disturbing thing about the tragedy Wednesday. Franklin High is not an inner-city school with gang activity. Drugs do not appear to be a big problem there. Social tensions of the kind that sometimes degenerate into violence do not seem to be a concern.

Just like many schools in our area.

But time and time again, school violence occurs in communities not so different from ours, in many ways. Focusing on dangerous environments as a means of predicting and forestalling such tragedies is, to a large extent, a waste of time.

So is attempting to prevent mass violence by banning or over-regulating certain types of firearms.

Once again we have been reminded that preventing all types of violence, including that in schools, requires a back-to-the-basics approach. More attention needs to be given to learning why people, both children and adults, lose control to the point they become killers.

Until we decide to focus on that, all the weapons restrictions we can legislate and all the security measures we can build into our schools will be useless.