Last week did not end well for four teenagers who were caught by a police drone while subway surfing in New York City, USA.

Subway surfing is an act of riding on the outside of a moving subway train, such as on the roof, between cars, or on the sides.

It is very dangerous and illegal.

While conducting anti-subway surfing operations, an NYPD transit drone team recently caught the four young individuals riding on top of an express train.

The boys, whose ages range age from 12 to 16 were apprehended.

The NYPD released a video of the incident, which shows the teens atop a southbound B train shortly after 16:00Hours on July 20, CNN reported, adding that one teen was arrested with six stolen MTA cards.

Two of the teens are 12 and 14 years old. They face multiple charges, including reckless endangerment and criminal trespassing.

Police in New York City are using drones to help catch people "subway surfing," but they're also warning that riding atop moving subway cars is dangerous — and illegal.

In a social media post, NYPD said that two days after the five teens were safely removed from the trains, a 16-year-old was critically injured for the same "dangerous stunt."

"If you see someone subway surfing, call 911. Ride inside. Stay alive," NYPD said in the post.