A teenager is recovering at the hospital after police and firefighters rescued him Monday night from one of the shafts of the Queensboro Bridge, New York City officials said Tuesday.

According to the FDNY, a 911 call about the incident came in just before 9 p.m. Officials said that when firefighters arrived, they found a person trapped inside the shaft of the bridge’s lower level, about 50 feet down, closer to the Queens side.

Police said the victim was a 16-year-old boy who had been climbing on the East River bridge as part of an apparent social media trend.

Video posted to Reddit appeared to show a sneaker next to a ladder leading down the bridge’s shaft as a voice called out repeatedly from inside.

FDNY Deputy Chief Nicholas Corrado told reporters the rescue operation was complex, requiring 10 different pieces of equipment and 75 emergency responders.

“This was a confined space operation, which is a very difficult, time-consuming, man power-intensive operation,” he said.

When the teen was finally freed from the shaft, emergency medical workers took him to NewYork-Presbyterian/Weill Cornell Medical Center. Police said he was in stable condition.

This is a developing story based on preliminary information from New York City officials.