NEW YORK >> A 32-year-old man who took a gun from a second man and shot him in the head during an altercation on a moving A train Thursday evening appears to have acted in self-defense and will not be criminally charged for now, the Brooklyn district attorney said today.

The shooting, which followed a frightening, chaotic confrontation on a crowded subway car during the evening rush, left the second man, 36-year-old Dajuan Robinson, in critical but stable condition. The gun he was shot with was one he brought onto the train and brandished during the altercation, the police said.

Oren Yaniv, a spokesperson for the district attorney, Eric Gonzalez, described the shooting as “shocking and deeply upsetting.”

“The investigation into this tragic incident is ongoing,” Yaniv said in a statement, “but, at this stage, evidence of self-defense precludes us from filing any criminal charges against the shooter.”

The confrontation between Robinson and the 32-year-old man, Younece Obuad, whom Robinson was harassing, occurred as the northbound A train pulled into Hoyt-Schermerhorn station in Downtown Brooklyn around 4:45 p.m., police said.

The men, whose names have not been officially released, were identified by three law enforcement officials with knowledge of the investigation and internal police records shared with The New York Times.

Robinson and Obuad did not know each other, the police said, and it was not clear how the altercation began. But cellphone video of the episode that captured the minutes leading up to the shooting shows Robinson screaming threats and racist remarks at Obuad.

The video also appears to show a woman on the train stabbing Robinson before the shooting occurred, and authorities were looking for her today.

In the video, Robinson is seen standing over Obuad, walking back and forth in front of him and repeatedly threatening him, saying “I will beat you up.” Eventually, Obuad stands, and the two men square off.

Robinson wrestles Obuad into a seat and then stands over him and pummels him. Just then, a woman rushes up and appears to stab Robinson in the lower back. It is not clear whether the woman knew Obuad before the encounter.

Robinson, blood seeping through his white T-shirt, pulls a gun from his coat and confronts both Obuad and the woman, who have moved to the far end of the subway car.

As panicked riders rush to the other end of the car, the video shifts away from the fight. Gunshots and screaming can be heard.

At a news conference today, Jeffrey Maddrey, the Police Department’s chief of department, said that Robinson had pulled out a gun during the dispute and that Obuad had taken it and shot Robinson.

The police released a video at the news conference that showed Robinson entering a subway station without paying a fare; it was not clear which station. The police said on Thursday that the altercation had started after Obuad got on the A train at the Nostrand Avenue station.

“Evidence is still unfolding,” Maddrey said today, adding, “Oftentimes, we see people enter into the subway station looking to cause harm, and they never pay the fare.”

Hermann Walz, a former state prosecutor and adjunct professor at John Jay College of Criminal Justice, noted in an interview today before Gonzalez announced his decision that it was ultimately up to the district attorney, based on the evidence, whether to file charges.

In June, a grand jury in Brooklyn voted not to indict a man who had fatally stabbed a passenger on a subway train. The man, Jordan Williams, 20, of Queens, stabbed Devictor Ouedraogo, 36, on a northbound J train, police said.

Ouedraogo had gotten into a dispute with other passengers, including Williams’ girlfriend, according to law enforcement officials. Witnesses said Ouedraogo threw the first punch, an official said.

In a radio interview today, Mayor Eric Adams said the shooting and the confrontation that preceded showed why state lawmakers should give the city more power to involuntarily remove severely mentally ill people from the subway.

The events, he said, “just really reinforces what I have been attempting to do.”

The shooting occurred a week after Gov. Kathy Hochul deployed hundreds of National Guard members and state troopers to check bags in the subway system. Hochul described the move as an effort to deter crime and ease riders’ fears. The altercation also came amid growing complaints that the Metropolitan Transportation Authority, the state agency that operates the subway, has not done enough to guarantee worker safety.

A string of violent episodes in recent years has left some subway riders on edge.

In 2022, Michelle Alyssa Go was on a subway platform in Times Square when a 61-year-old man pushed her from behind, shoving her to her death in front of a southbound train. Months later, there was a mass shooting on the R train in Brooklyn.

More recently, a 45-year-old crossing guard was fatally shot on a train in Brooklyn in January after intervening in a fight, and a 35-year-old man was killed and five other people were wounded after an argument broke out among teenagers on a train in the Bronx last month.

In response, officials introduced several anti-crime initiatives in the subway, including adding more police officers and increasing overtime pay for them, and began removing severely mentally ill homeless people from the system.

Still, the high-profile crimes have cast a particularly long shadow, and MTA surveys consistently show that some riders believe the system is dangerous.

But statistics paint a nuanced picture of subway crime in recent years. The data is further complicated by an increase in ridership since the pandemic.

This year, for instance, overall crime in the subway was up 13.2% through March 10, compared with the same period in 2023, but down 6.6% compared with the same period in 2022.

Annual data from recent years shows that major crime on the subway decreased slightly in 2023 compared with the year before even as ridership rose. But some crimes, including felony assault, have risen above prepandemic levels.

In a television interview last week, Hochul said that it was the public’s perception of subway crime, not statistics, that informed her decision to deploy the National Guard.

“We have seen a number of crimes, and again, not statistically significant, but psychologically significant,” she said, adding, “I can show you all the statistics in the world and say, ‘You should feel safe because the numbers are better,’ but you’re the mom on the subway with your baby in a stroller.”

In a post on the social media site X late Thursday, Jumaane Williams, New York City’s public advocate, said he had seen videos of the “terrifying moments” for straphangers and he implored Hochul to do more to increase subway safety.

Hochul, in a statement today announcing the first meeting of a transit safety task force, said she was “horrified by yesterday’s shooting.”

“The only way to solve the recent spike in subway crime is to collaborate across all levels of government,” she said.

Robinson, who appears to have once lived in Philadelphia, was convicted of robbery in Queens in 2014 and was sentenced to eight years in prison, according to court records. He was released in October 2019 and on parole until June 2022. He completed his period of supervised released without incident, a state prison system spokesperson said.

On Thursday, when the train where the altercation occurred arrived at the Hoyt-Schermerhorn station, which is served by the A, C and G trains and has a police outpost, officers there heard gunshots and responded immediately, Michael Kemper, the Police Department’s chief of transit, said at a news conference that day.

According to an internal police report, the first officer on the scene was engaged in a transit inspection when he heard four gunshots as the train pulled into the station. The officer took cover and saw a man run out of a subway car with blood on his face, at which point officers stopped him at gunpoint and placed him on his stomach, the report said.

The officers saw a man lying under the seats of a subway car, not moving and surrounded by blood, the report said. The officers also found a gun, a 38-caliber Ruger, a few feet away.

Robinson had two stab wounds to his lower back and “penetrating” wounds to the right side of his neck, the left side of his chest, his right temple and just below his right eye, which was ruptured, the report said.

Another video posted on X shows Obuad splayed on his stomach on platform steps. As Obuad is led away in handcuffs, Robinson can be seen lying on his back through the subway car windows. He appears to move his head very slightly as officers begin tending to him.

Moments later, Robinson can be seen lying on his side and facing the window, a red stain visible on his back, as officers in white gloves examine him.

Maddrey said the public response had been “incredible,” with videos recorded by people on the train giving “us additional evidence that we needed to piece together questions that we had.”

This article originally appeared in The New York Times.