The anger in East Flatbush is local. But the unrest that has gripped the Brooklyn neighborhood, including clashes with the police after officers fatally shot a 16-year-old, has been encouraged and incited by people coming from outside, community leaders said on Thursday.
The leaders appealed for calm a day after a vigil for the teenager, Kimani Gray, turned chaotic around Church Avenue late Wednesday night. Dozens of marchers were arrested and two officers were hurt, the police said. The crowds on the street swelled with local teenagers and seasoned organizers, including some members of the Occupy Wall Street movement.
It was the most sustained unrest in three consecutive days of vigils and marches. A protest the night before, in which people from outside the neighborhood were also prominent, ended without incident.
“It’s definitely outside influence who come in and start the crowd going and then leave at the end when all hell breaks loose,” said Gilford T. Monrose, a pastor who described the neighborhood as “hardworking families from the Caribbean who own these homes.”
Mr. Gray, who the police said was armed with a loaded .38-caliber revolver, was shot by two plainclothes officers on Saturday night after they said he pointed the weapon at them. They fired 11 times, hitting the teenager 7 times in the front and back of his body. He did not fire at them, though his revolver had four bullets in it.
“I can promise you that we will conduct a full and fair investigation,” Mayor Michael R. Bloomberg told reporters at City Hall. But he said the city would not tolerate the sort of lawlessness that followed the shooting.
The police said that all of those arrested on Wednesday lived in Brooklyn, though it was not immediately clear how many lived in East Flatbush, a neighborhood of low-rise apartments, single-family homes and bustling avenues.
Jenna Pope, 22, was among those who came from other neighborhoods to march Wednesday night in East Flatbush. “It didn’t happen where I live or to someone I know, but as an activist I believe that everyone is in this fight together,” she said.
The crowd was far different from those Ms. Pope saw when she lived at the Occupy Wall Street encampment in Zuccotti Park, she said. “It was mostly teenagers from the community,” she said, adding, “In the end, we’re all together and we support each other.”
Councilman Jumaane D. Williams, who was there on Wednesday, inveighed against those he saw as outside agitators, first on Twitter and then standing with other local leaders in front of a growing shrine to Mr. Gray on East 55th Street and Church Avenue.
“There are people, well intentioned though they may be, coming into the community and capitalizing on a situation and making it worse,” he said.
Mr. Williams said anger in the neighborhood was real and justified, but added that “it’s easy to take their anger and exploit it” but harder “to channel the anger properly.”
Before the leaders spoke, a police helicopter churned overhead in a sign of the tense atmosphere.
Some of the protesters who came from outside East Flatbush found fertile ground for an antipolice message in a neighborhood where many have voiced doubt over the official account of the shooting.
By Thursday, Mr. Williams was navigating a difficult strait as he sought to direct anger at police policies like the stop-and-frisk tactic, while resisting calls for a more pitched confrontation. The councilman — arrested in 2011 during the Occupy Wall Street demonstrations in Lower Manhattan — found himself pleading with protesters to calm the tone.
As Mr. Williams referred to the lack of attention paid to violence committed by black youths against each other, a man standing at the edge of the crowd of reporters began speaking over him. “This is a police brutality issue,” said the man, Jose LaSalle, 43, an activist on police issues from the Bronx. “Let’s not boil things down and sugarcoat them.”
Some standing at Mr. Williams’s side moved to quiet the man. One shouted: “You are agitating the community, you are agitating those young kids. You are part of the reason there was a problem last night.”
Another man standing next to Mr. LaSalle, shouted: “I’m from this area, born and raised.” The man, Omowale Adewale, 34, continued: “Ask the youth in the community what they want!”
“There is a full discussion that needs to be had,” Mr. Williams said, trying to wrest back control without addressing the men. “If you want to address only one part of the discussion, you are being destructive to the community.”
“Investigate the investigators!” another man, Dave D. Douglas, 26, a union steamfitter born in East Flatbush, called out a few minutes later.
As many in East Flatbush braced for another confrontation, Mr. Gray’s mother, Carol Gray, told reporters that her son was a “regular teenager” with a 10 p.m. curfew who had been “sold prison culture.” She said he had just left a 16th birthday party when officers confronted him on Saturday night.
Wearing sunglasses and a black scarf over her head, Ms. Gray paused occasionally to compose herself. “Why did the police fire the first bullet? Why the second bullet?” she asked, counting the shots on her fingers. “Why the third bullet? Why the fourth bullet? Why?”
She said her son died only a block from the home where he had lived when he was younger.
Councilman Charles Barron, who sat at Ms. Gray’s side and occasionally consoled her, said that while some had called for peace, “our call is for justice.”