Seventeen teenagers and young adults who the authorities say belonged to three street gangs that formed an alliance in Brooklyn were charged on Tuesday with unleashing a wave of violence that left four people dead and 10 others wounded in shootings.
The gangs, made up of young people from the Brownsville, East New York and Fort Greene neighborhoods, joined forces in an “umbrella” gang known as YPF to expand their territory and increase their access to guns, Eric Gonzalez, the Brooklyn district attorney, said.
The young men and women, ages 17 to 23, face charges that include second-degree murder, assault and criminal weapon possession. A spokesman for Mr. Gonzalez said that 14 of them were in custody on Tuesday and would be arraigned later in the day. It was unclear whether any of those charged had lawyers as of Tuesday evening.
“I’m going to tell you that we know that law enforcement by itself can’t end gang and gun violence,” Mr. Gonzalez said at a news conference on Tuesday. “But today’s indictments are a big step in getting justice for the victims and improving public safety.”
Mayor Eric Adams, who also appeared at the news conference, said that the kind of takedown that resulted in the arrests should be duplicated across New York City.
“We’re not going to live in a culture of violence and we won’t be defined by the crisis of violence,” he said. “That is not who we are as a city. We deserve better, and today, the district attorney showed us that we’re going to get better.”
Mr. Gonzalez said the authorities were trying to crack down on “senseless gang and gun violence.” He announced last week that homicides and shootings in the borough had declined in 2021 from the year before and he cited gang takedowns as one reason for the drop.
Law enforcement experts and civil rights advocates have long taken issue with the anti-gang tactics used by law enforcement agencies in New York. These critics say the police often rely on unreliable information in carrying out such actions, classifying too many young men of color as gang members.
Mr. Gonzalez has previously said that gang takedowns done for the sake of appearing tough on crime are meaningless and destructive and that they ignore the main reason people join gangs: for protection.
But he has also said the tactic can be useful when the authorities focus on people who engage in violence.
“These investigations are complicated, they’re challenging, but they’re effective and they are necessary,” he said on Tuesday.
Mr. Gonzalez said a “disturbing aspect” of the case announced on Tuesday was the ages of those who were charged. When the investigation began in March 2019, some were as young as 14.
“That is heartbreaking that some of our youngest residents in our county are involved in this gang and gun violence,” he said.
Investigators said the gang members had decided to form the larger alliance under the YPF banner to increase their numbers and geographic dominance, and to expand the territory where they could travel safely.
“As part of this alliance, they all agreed to adopt the rivalries and the enemies of the other gangs,” Mr. Gonzalez said. “So this alliance not only brought these three gangs together and created one bigger gang, but it also increased the amount of violence.”
He said the alliance was behind more than a dozen shootings, including one at MetroTech Center in Downtown Brooklyn in September that resulted in a New York University student being shot in the arm.
At the news conference, officials showed surveillance video from an October 2020 episode that they said showed two alliance members firing shots inside a bodega in East New York.
Sherard McKoy, an 18-year-old college freshman who officials said did not have gang ties, was killed in the shooting. Mr. Gonzalez said that although Mr. McKoy was not the intended target, he was with an alleged rival of the two gunmen.
“He was an 18-year-old college student, a freshman,” Mr. Gonzalez said. “A young man who enjoyed playing basketball and had ambitions of being a New York City schoolteacher.”
Daijyonna Long, 20, of Virginia, was another victim of the alliance’s coordinated attacks on their rivals, officials said. Ms. Long died after being shot at a birthday party in Brooklyn that the authorities said alliance members showed up to uninvited.
Surveillance video shown at the news conference captured what officials said were two alliance members and two other people opening fire in the apartment building lobby where the party took place.
“She never made it back home to Virginia,” Mr. Gonzalez said of Ms. Long.
Five of those charged face life sentences if convicted of the most serious charges, Mr. Gonzalez said; others face up to 25 years in prison.
Ashley Southall contributed reporting.