Last week, a 2-year-old boy in Milwaukee found a handgun in the back seat of a car. Then, he accidentally shot his mother through the front seat. His mom died at the scene.

The story is horrifying. But a new Washington Post analysis by Christopher Ingraham finds this type of situation — in which a toddler up to 3 years old picks up a gun and shoots someone — has happened at least 23 times this year.

Most of the cases do not play out like the Milwaukee case, in which a toddler shoots someone else. According to Ingraham, in 18 of 23 shootings, the kids shot themselves, and nine died as a result of their self-inflicted wounds.

Whether adults face charges over these kinds of shootings depends on state laws. Child access prevention laws, for instance, can impose criminal penalties on adults who allow kids to have unsupervised access to guns.

In total, this type of shooting appears to happen more than once a week, according to the Washington Post's analysis. What's worse, America seems to be one one of the few developed countries that deals with these levels of gun violence.

These shootings make up a small portion of all gun violence in America

While obviously tragic, the toddler shootings are a small part of all shootings in America. So far this year, the Gun Violence Archive database has tracked more than 16,900 incidents of gun violence, more than 4,300 of which resulted in deaths. Among those incidents, 182 children up to 11 years old were injured or killed.

When it comes to young child victims in particular, a previous study by researchers David Hemenway and Sara Solnick found that 110 US children ages 0 to 14 die in accidental shootings each year.

Different factors contribute to each of these accidental shootings, but they do appear to happen far more in the US than other developed nations. A 2011 study co-authored by Hemenway, who heads the Harvard Injury Control Research Center, found that in the US, unintentional firearm death rates of children ages 0 to 14 are about 10 times higher than in other developed countries.

America's high levels of gun ownership contribute to the toll of violence

One cause for the extraordinary number of shootings in America: easy access to guns.

The US has the highest rates of private gun ownership in the world, in part thanks to gun laws that are looser than other nations' restrictions. Based on a 2007 survey, the number of civilian-owned firearms in the US was 88.8 guns per 100 people, meaning there was almost one privately owned gun per American and more than one per American adult. The world's second-ranked country was Yemen, a quasi-failed state torn by civil war, where there were 54.8 guns per 100 people.

At the same time, studies show gun ownership increases the chances of shootings. According to a 2014 meta-analysis published in the Annals of Internal Medicine, people with access to guns are twice as likely to die in gun-related homicides and more than three times as likely to kill themselves than those who don't. Looking at the evidence, the American Academy of Pediatrics similarly concluded, "The absence of guns from children's homes and communities is the most reliable and effective measure to prevent firearm-related injuries in children and adolescents."

That helps explain why the research shows restrictions on guns can help prevent gun deaths: A 2016 review of 130 studies in 10 countries, published in Epidemiologic Reviews, found that new legal restrictions on owning and purchasing guns tended to be followed by a drop in gun violence — a strong indicator that restricting access to guns can save lives.

Guns are not the only factor that contribute to violence. (Other factors include, for example, poverty, urbanization, and alcohol consumption.) But when researchers control for other confounding variables, they have found time and time again that America's high levels of gun ownership are a major reason the US is so much worse in terms of gun violence than its developed peers.