Firearms have surpassed car accidents as the leading cause of death among American children, with official data showing a significant increase in gun-related homicides, such as the killing of 19 children in a Texas school rampage.

According to the Centers for Disease Control and Prevention (CDC), 4,368 children and adolescents under the age of 19 died from firearms in 2020, a rate of 5.4 per 100,000.

The CDC found that 4,368 Americans under the age of 19 died as a result of gun violence in 2020, a 29.5% increase from 2019.

That's a 63% increase over the 3.3 per 100,000 figure observed a decade ago.

Although the cause of the increase is unknown, the result is consistent with other recent research that demonstrates an increase in firearm-related injuries at the start of the COVID-19 outbreak.

It's also the first time that firearm-related injuries have surpassed motor vehicle crashes as the leading cause of death among children since the CDC began keeping track.

Gun deaths have been second to motor vehicle crashes as the top cause of death among children and adolescents for the past 21 years; however, the gap between the two categories has been closing since 2016, according to the CDC.

In 2020, roughly five Americans aged 19 and under were killed in motor vehicle accidents.

Since 1999, the number of children and teenagers killed by cars has decreased by more than half.

Significant progress has been made in lowering the death rate of motor vehicle crashes, including increasing the use of seat belts and safety technology such as automatic emergency braking systems and airbags.

The mass shooting at an elementary school in Uvalde, Texas, on Tuesday, has refocused attention on gun injuries.

At Robb Elementary, 19 students, including third and fourth graders, as well as two teachers, were killed in what President Joe Biden described as an act of "carnage."

"It's a senseless act of violence," Dr. Jason Goldstick, an associate professor of emergency medicine at the University of Michigan, told ABC News. "You shouldn't be expected to be exposed to violence when going to school like that."

The capital city of Washington had the greatest number of gun-related deaths, followed by Louisiana and Alaska.

The data showed that, while mass shootings like the one in Uvalde are terrifying, they account for a small percentage of total child gun deaths.