PATERSON, N.J. — The combatants agreed to meet in a law office, in one of those ancient brick mills that cast shadows of Paterson’s flourishing past over its hard streets. This beef between up the hill and down the hill had to end, now that another child had died of gunfire. A basketball prodigy. A boy.

Street-smart elders had demanded the meeting, so here came teenagers and young adults from both neighborhoods last Monday night, slouching in the conference room’s red-leather chairs, leaning against a wall featuring a portrait of John Lennon. They quickly squared off like aggrieved litigants.

The tension between pockets of the these up-and-down neighborhoods in Paterson, considered one of the most violent small cities in the country, goes so far back that no one remembers how it began. But knives had replaced fists, and guns had replaced knives, and now Armoni Sexton, 15, a silky 6-foot-7 player with a shot at a world beyond, was dead.

“Why this kid?” Kenyatta Stewart, a lawyer who helped arrange the meeting, said, echoing the question that nagged those in the room. “Why do you pick the most talented, the tallest — the kid we all expected to be the next one?”