Kimani "Kiki" Gray, 16, was shot by two plainclothes officers who said Gray flashed a handgun then pointed it at them when they approached the stoop where he and others were sitting in the East Flatbush section of Brooklyn.
Gray, who the New York Daily News said may be linked to a street gang, was not armed, his family insists. Police said a loaded .38-caliber revolver was recovered from the scene.
Monday night, mourners gathered at the site for a vigil. The group then began what was at first a peaceful march toward the NYPD 67th Precinct, some 20 blocks away.
The New York Times said some of the marchers, about two dozen young people, broke away from the group and began smashing car windshields. Witnesses told the newspapers the rioters trashed a bodega and assaulted a manager and customer at a Rite Aid drug store.
They hurled projectiles at officers who arrived to quell the violence.
Many witnesses were sympathetic, saying young blacks in the neighborhood are frequently harassed by the NYPD, which has a stop-and-frisk policy they argue amounts to racial profiling.