Senseless shootings in schools are too often in the news these days. But how does anyone explain the latest incident in Arkansas where young men - children, really - ages 11 and 13 carried out a calloused ambush of peers and teachers? It defies rational explanation.

One can only speculate as to what would set anyone off, young or old, in such violent fashion. The only certainty is the appalling nature of the crime and tragic aftermath in loss of life and serious injuries on such a widespread scale. That and the loss of innocence for a school full of youngsters and adults who may carry psychological and emotional scars to their own graves.One girl, who saw her friend shot dead next to her, expressed fear at returning to school. "I feel like I'm living a nightmare." Indeed, those must be the sentiments of anyone even remotely connected with the incident.

Bad dreams cannot get much worse than the shooting of four girls and a teacher and the wounding of 11 others outside a middle school. What could prevent future episodes is a mystery. What caused this one is unclear. There are, however, several things to consider.

One of the two perpetrators had threatened extreme violent action, apparently after being spurned by a young girlfriend. He had spoken with school counselors of his feelings. While it would be unfair to second-guess with 20-20 hindsight, it is obvious now that someone should have seriously listened to those desperate rantings and sought earlier intervention.

Of course, that in no way places responsibility on anyone but the youths. But despondency mixed with desperation, a dose of adolescent hormones and perhaps even drugs or alcohol can be a lethal combination. Easy access to firearms fueled the scenario.

How much of a desensitizing effect has violence in media and entertainment had on the killers and so many others in society? Behavioral scientists debate media effects, but common sense and ample anecdotal evidence points to adverse impact on someone watching and hearing repeated acts of often graphic violence.

On the screen, the full consequences of such actions are seldom accurately portrayed. That aftermath includes tragic loss and emptiness in families and the long-term remorse and regret that usually accompanies such deeds.

One sad and sure thing is that four young girls and an English teacher are dead, another teacher's life hangs in the balance, and two young men and their families have a lifetime to contemplate the horror of an inexplicable deed that shattered lives and shocked a nation.