At first, the videos appear innocuous, showing three people standing side by side. But unlike other clips on the popular social media app TikTok, the users in these videos don’t break into a coordinated dance number or act out a funny sketch.

Instead, two people target the person in the middle, swiftly kicking their legs out from under them and sending them painfully to the ground.

Known as the “skull-breaker challenge,” a reference to the victims’ heads hitting the ground as they tumble backward, the dangerous routine has gone viral in recent months. Parents, school administrators, doctors and law enforcement officials who are seeing young people nationwide land in hospitals with serious injuries are horrified.

On Tuesday, the Camden County Prosecutor’s Office in New Jersey did something about it. Prosecutors charged two minors with third-degree aggravated assault and third-degree endangering an injured victim following a January incident related to the prank.

According to a news release from the office, the prank caused another minor to suffer a seizure as well as a head injury and concussion.

While the names and ages of those involved were not released by prosecutors because they are juveniles, Stacy Shenker of Cherry Hill, N.J., told NBC News that her 13-year-old son had been injured at school Jan. 24.

After arriving at the school, Shenker said she was told by first responders that her son, who was unresponsive at the time, had a seizure.

“Initially, we didn’t know what happened,” she said, noting that her son spent more than a day in the hospital. “At that point, we had never heard of the prank.”

The Shenkers aren’t alone in their experience. Recent reports detail similar cases in which unwitting participants of the “skull-breaker challenge” were hospitalized.

Last month, an Alabama mother posted on Facebook that her son broke two bones in his wrist and needed surgery after he was “unknowingly tiktok pranked.”

In the prank, one person is tricked by two others into jumping for a video. Then, when the person is in midair, the other two swipe at the victim’s feet, sending the victim tumbling to the ground.

Prayers needed... Parker was unknowingly tiktok pranked which caused him to fall. We are sure broken arm but not sure...

Posted by Teri Wimmer Smith on Tuesday, February 11, 2020

The prank has caused injuries in Pennsylvania, Oregon and Arkansas, and other states.

One sixth-grader said she “went numb” after hitting the floor and struggled to get up on her own. A 14-year-old remembered “blacking out for a second” before getting “an instant pressure headache.”

Amid rising concerns about safety, TikTok issued a bulletin Thursday encouraging its millions of users “to exercise caution in their behavior whether online or off.”

“The safety of users is our top priority at TikTok, and we do not allow content that encourages or replicates dangerous challenges that might lead to injury,” the post said. “In fact, it’s a violation of our Community Guidelines and we will continue to remove this type of content from our platform.”

A spokesperson for TikTok reiterated the platform’s policy on potentially harmful content in an interview with The Washington Post early Wednesday, stressing that people who attempt stunts such as the “skull-breaker challenge” won’t be rewarded with viral fame.

“It’s not going to make you TikTok-famous, so don’t do it,” the spokesperson said, later adding: “It’s not fun. It’s not funny.”

Several TikTok users posted videos on the app aimed at deterring people from trying the prank.

“People don’t see how serious this is,” one verified user said in her video. “I want to spread awareness for this to stop.”

@kelly_kikx

Your safety comes first! Your life is worth more than a challenge. ##stopskullbreaker ##skullbreakerchallenge cc: @liamstoffbergg @bryankazaka

♬ Original sound - vbankzs

Shenker told Patch.com in an interview that her son has yet to fully recover.

“He’s doing better, but he feels like he’s being punished because he can’t do the things he likes to do,” she said. Shenker added that the long-term effects of the boy’s injuries are unknown.

“We need to make sure this doesn’t happen to anyone else,” she said. “They’re 13-year-old boys, and they just don’t think.”