The murder was the first killing on the subway in more than a year.
Chief of Detectives Dermot Shea said the killing stemmed from a feud between rival gangs. The victim, Abel Mosso, 20, was believed to be a member of the 18th Street gang, he said.
The gunman, whom police did not immediately identify, had been charged in December by the Queens district attorney in a gang conspiracy case, and is a known member of MS-13, a Salvadoran street gang, police said.
“Gang incidents within transit are extremely rare,” Shea said. “When you have an incident like this, you’re going to get the full might and fury of the NYPD.”
The shooting, which was caught on video by a bystander, occurred around 12:45 p.m. Sunday, after a fight on a crowded 7 train bound for Manhattan spilled out onto the platform at the 90th Street-Elmhurst Avenue station in the Elmhurst neighborhood.
This article originally appeared in The New York Times.