Shadale Graham was killed when two gunmen opened fire after an argument on Sunday evening, police said.
The incident occurred after a fight between the shooter and a 17-year-old student at the school.
The Harlem Youth Marines left the Harlem Armory last year. They are now at 123rd St. and Third Ave.
Shootings in Jamaica decreased by more than 30 percent last year.
Rapper Jamal Green, or Mazaradi Fox, was shot and killed by Jamal Scott, police said.
Lloyd Morgan Jr. was hit by a stray bullet in The Bronx on July 22, 2012.
Authorities provided a two-page glossary of slang and code words used on social media and taped calls.
As the nation mourned the Connecticut victims, New York City remembered another murdered principal.
The drive-by shooting on July 29 left Ariyanna Prince, 2, and five others wounded.
Members of the Trinitarios face charges including gun trafficking, murder and drug dealing.
Judge Edward McLaughlin's plea for Harlem to oust gang violence resonated with local advocates.
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