CNN
 — 

A 3-year-old girl fatally wounded her 4-year-old sister in an unintentional shooting in Texas, Harris County Sheriff Ed Gonzalez said.

“This basically involves a 3-year-old and a 4-year-old,” Gonzalez said. “The 3-year-old is the alleged shooter. It appears to be unintentional.”

Calling the incident “tragic” but “very preventable,” the sheriff said a group of family and friends – five adults and the two children – were hanging out inside a Houston apartment on Sunday. At one point, the children were unsupervised in a bedroom because each parent thought the other was watching them, he said.

The 3-year-old got hold of a loaded semiautomatic pistol, Gonzalez said. The family heard a gunshot and ran into the room, where they found the 4-year-old girl unresponsive on the floor.

“It just seems like another tragic story of another child gaining access to a firearm and hurting someone else,” Gonzalez said.

The sheriff said the investigation is ongoing and noted that, in situations like this, it is “very likely” that someone faces charges for failing to secure the weapon.

The shooting is just the latest instance of a child using an unsecured firearm and causing tragedy. The most prominent such shooting recently involved a 6-year-old boy who shot his elementary school teacher earlier this year in Newport News, Virginia; the teacher is recovering.

There were at least 2,070 unintentional shootings by children under 18 years old between 2015 and 2020, resulting in 765 deaths and 1,366 injuries, according to data compiled by Everytown Research & Policy, the research arm of the group that advocates for gun control and against gun violence. About 39% involved a shooter 9 years old or younger, the non-profit said.

Firearm-related injury recently surpassed motor vehicle crashes to become the leading cause of death among people 1 to 19 years old in the US, according to a 2022 paper published in The New England Journal of Medicine. In that, the US stands alone among world powers.

“In no other similarly large or wealthy country are firearm deaths in the top 4 causes of mortality let alone the number 1 cause of death among children,” a Kaiser Family Foundation study wrote last year.

The American Academy of Pediatrics recommends gun owners keep their firearms locked up and unloaded, with ammo locked in a separate safe.