NEW YORK — Two teenage girls were discovered dead on top of an incoming J train at a Brooklyn subway station early Saturday and appeared to have been subway surfing, the deadly, social media-fueled trend popular among some New York City youth, authorities said.

Officers responding to a 911 call found the girls unconscious shortly after 3 a.m. on the roof of the last car of a train at the Marcy Avenue station in Williamsburg that had just crossed the Williamsburg Bridge from Manhattan. They were pronounced dead at the scene. Their names and ages have not been released.

“It’s heartbreaking that two young girls are gone because they somehow thought riding outside a subway train was an acceptable game,” Demetrius Crichlow, the president of New York City Transit, said in a statement Saturday. Subway surfing, in which people ride atop or hang off the sides of fast-moving trains, has been around since the transit system’s earliest days more than a century ago.

— The New York Times