The Wal-Mart in Hayden, Idaho, on Tuesday. (Kathy Plonka/Spokesman-Review via AP)

The shooting death of an Idaho woman on Tuesday has drawn national attention owing to the particularly nightmarish circumstances: Police said that a woman, Veronica Rutledge, was accidentally shot by her 2-year-old while inside a Wal-Mart. Her father-in-law told The Post that Rutledge received a purse with a special pocket for a concealed weapon for Christmas, a compartment that had to be unzipped to find the weapon. The 2-year-old boy “doesn’t know where his mom is” right now, Rutledge’s father-in-law said, compounding the tragedy.

It was not unusual that Rutledge, described by her father-in-law as a gun lover, was carrying around a loaded weapon. Nor was her carrying a loaded gun remarkable for the region, where “a lot of people carry loaded guns,” a spokesman for the Kootenai County sheriff’s office told the New York Times.

What we do not know is just how often a child accidentally shoots and kills someone. We looked into the subject earlier this year after a 9-year-old girl in Arizona accidentally shot and killed her shooting range instructor with an Uzi, another shooting death that was so unusual — involving a child, an Uzi and a dead adult — that it was able to break through the noise and actually demand more attention, something that does not happen most of the time with gun deaths. And we were told at the time that the people and agencies who keep an eye on shooting deaths did not know for sure how often it happens.

It is a strange gap, this lack of information on accidental shootings involving children. This data is out there, of course, but the various agencies that compile statistics regarding shooting deaths said it has not been pulled together nationwide. There are media reports after these things happen, story after story after story of such unintentional shootings. And there are some systems that try to pull together the relevant numbers. The National Violent Death Reporting System, for example, combines information from death certificates, medical examiners and law enforcement reports to try to produce such data, but it operates in just 18 states.

The gap here is also accompanied by a larger one: uncertainty regarding the number of accidental shootings overall. The Centers for Disease Control and Prevention said there were 32,351 shooting deaths in 2011. Of those, 591 were deemed accidental, the CDC said. But these records rely on causes of death as determined by medical examiners, coroners and attending physicians, which may not be foolproof. A New York Times investigation last year found wildly inconsistent rulings from medical examiner rulings in several states.

Jon S. Vernick, co-director of the Johns Hopkins Center for Gun Policy and Research, told me in August that medical examiners could be reluctant to characterize a death as accidental if they are not certain, so they could label it as undetermined. Or, he said, if a teenager pulls a trigger of a gun that he or she incorrectly thought was unloaded, then shoots someone, that could be ruled a homicide. Either way, he said, this “muddies our data” and makes it harder to see trends over time.

Nationwide data on accidental shootings could help show “what works to prevent” accidental shootings, Vernick said at the time.

“It’s important to know the scope of a particular problem,” he said. “For motor vehicle crash deaths, when there’s a particular car that’s posing a higher risk, we can figure that out. But if you want to know, is there a particular gun posing a greater risk for all deaths, we can’t answer that question.”

(For more, read our earlier post on the subject.)

Related: We also don’t know how many times police officers shoot and kill people each year.