You start the process - given that doing so will take a long time. But I think that just arming and/or protecting those who might be vulnerable to such attacks isn't any long-term solution, given any who wish to target the innocent might find other ways. I don't know about this particular incident but many of these attackers do seem to want to cause the most grief to the most people, and hence why they choose the youngest, most vulnerable, and usually, the most loved, given that this will impact so many. So the children are not usually hated but used as a proxy to get at others. One only has to look at such incidents around the world, since violence by guns is not the only method used. But guns do tend to make it much easier.