When do you speak to your children about school shootings?

So it seems that school shootings will stay on a continuous rise without interference for actual help from the government . Obviously in schools they teach kids about lock downs and procedures.. but do you think parents should be talking to their children about active school shooters, and what to do? This world is such a scary place and I want my child to be prepared for everything and I want him to have all the mental tools possible to handle what comes at him. But I also don’t want to scare him. So what do we think? Do you speak with your children and try and explain what to do in the situation? Or at least explain to them the importance of listening to the teachers? Or do you just pray that the government fixes this gun issue ??