When the wolf comes, make a stand.
When the police arrive, what do they bring? Guns. Lots of guns and men trained and prepared to use them. But the most important thing they bring is the will to act. Even without the guns, that's what makes them effective.
Know there are situations where you will be disarmed. (Airplanes, schools, courthouses, etc.) Plan accordingly. Find something that makes sense to you. Train regularly. Plan. Armed or not, make a stand.
If someone says to you this week, "Never again", agree with them. Never again should healthy adults stand there and answer questions about their religion and wait to be shot in the head.
We should train our children, too. In a classroom full of people, one shooter should be buried in book bags, chairs, and desks, and neutralized as a threat by trained and motivated people. At the first sight of the weapon, everyone should respond. We train for fires, why not other threats?