What a great question. It is SO hard knowing how to deal with distressing and violent news, and all the more so when it has become so terribly common. We’ve found it helpful to process these realities along with our kids by talking about it all together as a family, usually in some way that feels natural (like if we all hear an announcement about it on tv or radio). Since they are already hearing about it, and increasingly so, we want to be available to answer questions and provide support wherever they’re at. We just make sure to follow their lead about what information they want to get into or time they want to spend talking about it.
It's hard to know that you're doing the right thing, but I think talking about it is unavoidable, considering that kids are aware of this in some way whether because of school drills, hearing adults talk, or in our case, because one of the events hit close to home. We talk about it a little at a time, in a way that's appropriate for the ages of my kids.