(1) multiple reports are saying that many of the kids "protesting" for gun control are following scripts provided for them. Many are not even kids. In general, young people appear to be more in favor of the right to keep and bear arms than older generations. Why is no one listening to them?
(2) why not tell kids that shit happens? It's the truth. They'll have to learn it some day.
With small children we try not to scare them unnecessarily, and so it is common to tell some comforting lies - but if they are old enough for us to take their political opinions seriously, then they are old enough to know the truth: shit happens. There's no such thing as perfect security. All we can do is to manage overall risk.