The parents, the teachers, the students of Chardon, Ohio, never saw it coming, nor did those in Littleton, Colo.
Until a relatively few years ago, the prospect of children or adults bringing guns into schools and using them to kill children was unthinkable. No one would do such a thing, surely.
And yet, at Columbine High School, in a matter of less than an hour, two heavily armed students killed 12 of their peers and a teacher before turning their weapons on themselves. That was in 1999.
Last week, a student from another school began firing in Chardon High School, killing three students and injuring another.
Between those two tragic and bloody incidents, there have been numerous others that have ended without bloodshed, incidents in which guns have shown up in schools.
It can happen; it does happen.
This week, law enforcement personnel from around Warren County have been visiting schools, not so much to work with children, but to prepare themselves and plan ahead for the unthinkable. Armed with their police training and architect's drawings to familiarize themselves with the layout of the schools, they were filing information and loading strategy to deal with a number of potentially tragic scenarios.
They were there to protect our children, the most fragile, the most vulnerable, and the most precious things in our lives.
We owe these law enforcement professionals our respect, our thanks and our cooperation.