A group of young New Yorkers’ antics recently turned life-threatening after a 15-year-old’s arm was amputated on a subway track.

The incident went down on Monday morning after four friends decided that it would be cool to “subway surf,” aka ride on top of the subway train rather than inside of it.

However, one of the teens lost his balance while “surfing” near the Jackson Heights-Roosevelt Avenue station in Queens, ABC7 New York reports.

He ultimately landed on the track, and a northbound train departing from the station severed the 15-year-old’s arm.

“We know he was subway surfing on the outside of the car,” a Metropolitan Transportation Authority (MTA) employee noted, according to the New York Post. “Usually when you’re subway surfing, you have to get off the train before the tunnel. He must’ve missed that point.”

“They found his arm under the train,” the employee added, pointing out that it was severed “from the elbow down.”

Another eyewitness named Christian Mojica also spoke on what he saw that day.

“I got off the F train, and I saw the police putting up the tape and the actual body on the floor,” Mojica recalled, according to ABC7 New York. “I didn’t want to see it. It’s not pretty. I saw face, blood, a person slumped over, and I just left.”

“It’s very traumatizing, and I hope everybody there is able to come back from, because it’s not nice,” he continued. “I wish the best for anyone who is related to him.”

The teen was transported to Bellevue Hospital and is reportedly in stable condition.

“A preliminary investigation determined that the male was struck by a northbound R train as it was pulling away from the station,” a New York City Police Department (NYPD) spokesperson noted, according to The Independent. “The aided is not believed to be the victim of a crime. The investigation remains ongoing at this time.”

This incident is the latest example of subway surfing, a trend that’s risen in popularity by over 500%, according to PEOPLE, turning dangerous or even deadly.

In fact, the outlet reports that there have already been 627 reported instances of people riding outside of subway cars in 2022, and another New Yorker lost his life while subway surfing less than a year ago.

“Riding outside of subway cars is reckless and extremely dangerous. This behavior can result in awful consequences, as it likely has for the young man who was severely injured on Monday,” Pat Warren, the MTA’s chief safety and security officer, said in a statement to PEOPLE.