There have been at least 209 unintentional shootings involving children ages 17 and younger in the United States this year, according to Everytown, the gun safety advocacy group dedicated to reducing gun violence in America.

And according to the Washington Post’s Christopher Ingraham — who did his own analysis of news reports of such shootings — there have been at least 43 cases of shootings involving toddlers ages 3 and younger in 2015, or roughly one per week.

And in 31 of them, the Post reports, a toddler found a gun and shot himself or herself, with 13 of those self-inflicted gunshot wounds proving fatal.

The most recent fatal toddler shooting appears to have occurred in August, when police say a 21-month-old toddler in the St. Louis area found a handgun at his grandmother’s house and accidentally shot himself in the torso. The child was taken by his mother to an area hospital, where he was pronounced dead.

A week earlier, police in Alabama said a 2-year-old accidentally shot his father in the head and killed him after the boy’s mother had left work. She returned home and discovered her husband dead in their Hoover, Ala., apartment.

“‘Horrible tragedy’ is as close as I can come to putting words to it,” Hoover Police Capt. Gregg Rector told the Washington Post. “You think you’ve seen everything in this line of work and then something like this happens.”

But cases like it are not uncommon, the Post found. There were at least 12 cases in which a toddler shot someone else this year, the Post found, including two that resulted in death. In April, police in Cleveland said a 3-year-old boy shot his 1-year-old brother in the head and killed him.

The vast majority of toddler shootings this year involved boys, according to the Post’s report.

According to the Centers for Disease Control and Prevention, there were 33,169 total shooting deaths in the United States, including 505 determined to be unintentional.

Last month, the CDC said that there was no nationwide data “regarding the age of the person who pulls the trigger in an unintentional shooting.” Everytown, though, counted 100 unintentional gun deaths of children 14 and under, 61 percent more than reflected by CDC data.

The common denominator in most of these accidental shooting cases is that guns are left unsecured by parents or guardians. According to Everytown, more than 2 million American children “live in homes with guns that are not stored safely and securely. According to the group’s 2014 report “Innocents Lost: A Year of Unintentional Child Gun Deaths“:

About two-thirds of these unintended deaths — 65 percent — took place in a home or vehicle that belonged to the victim’s family, most often with guns that were legally owned but not secured.

More than two-thirds of these tragedies could be avoided if gun owners stored their guns responsibly and prevented children from accessing them. Of the child shooting deaths in which there was sufficient information available to make the determination, 70 percent (62 of 89 cases) could have been prevented if the firearm had been stored locked and unloaded. By contrast, incidents in which an authorized user mishandled a gun — such as target practice or hunting accidents — constituted less than thirty percent of the incidents.

Not depressing enough? The Post’s report on toddler shootings includes a few sad caveats,according to Ingraham:

These numbers are probably an undercount. There are likely instances of toddlers shooting people that result in minor injuries and no media coverage. And there are probably many more cases where a little kid inadvertently shoots a gun and doesn’t hit anyone, resulting in little more than a scared kid and (hopefully) chastened parents.

Notably, these numbers don’t include cases where toddlers are shot, intentionally or otherwise, by older children or adults. Dozens of preschoolers are killed in acts of homicide each year, according to the Centers for Disease Control and Prevention. But I haven’t included those figures here.