It isn't often that a shooting death captures national attention these days. As projects over the last two years by Slate and Joe Nocera demonstrated, there are dozens of gun deaths that go mostly unremarked every day. Even mass shootings fly under the radar of a desensitized nation.

Occasionally, though, a death can genuinely take Americans' collective breath away. One of those happened Tuesday in Hayden, Idaho, where a 2-year-old accidentally fired his mother's concealed pistol in a Walmart, killing her. There are many reasons this particular killing might get such attention: It's the holiday season; the news is slow; the victim, Veronica Rutledge, was a young mother, just 29; it happened at a Walmart, a place with which nearly every American is familiar.

But the obvious difference is the horror of a 2-year-old who, according to news reports, wasn't even aware of what had happened, accidentally killing his own mother. How could such a thing happen? How often does it happen? The answer, as with so many questions about gun violence, is that we simply don't know. There aren't reliable statistics on gun incidents involving kids.

Let's start with Idaho. As The New York Times notes, reporters asked a sheriff's deputy why she would have brought a firearm to shop. “It’s pretty common around here—a lot of people carry loaded guns,” he said. That's at least relatively true: Idaho has one of the highest gun-ownership rates in the nation. Rutledge had a concealed-carry permit, and a report by an anti-gun-control group in July found that the state is near the top for percentage of residents with permits. It's unclear what sort of gun was used or what exactly happened, though police said safety measures were followed. Rutledge's father-in-law said the gun was kept inside a zippered pouch, but the child managed to open it.