In the wake of Baltimore’s first student slaying on school grounds in almost eight years, schools chief Andres Alonso sent a somber e-mail to teachers, administrators and parents to try to boost their spirits.

“We don’t yet know why a 15-year-old student was stabbed to death outside William H. Lemmel Middle School,” he wrote on Tuesday. “We may never know the exact reasons, but in a sense we already know the cause. This young man was a victim of the youth violence that has long been, and continues to be a horrifying facet of our society.”