(NEW YORK) — A man who was initially a person of interest in the investigation into a shooting on a rush-hour subway train in New York City’s Brooklyn borough was named a suspect on Wednesday morning, according to the mayor’s office.

New York City police are still searching for 62-year-old Frank R. James. There was a $50,000 reward for information leading to his whereabouts.

“At this time, based on the preliminary investigation, we believe he was alone,” New York City Mayor Eric Adams told ABC News’ George Stephanopoulos in an interview Wednesday on Good Morning America.

The shooting unfolded on a Manhattan-bound N subway car during the Tuesday morning commute, just before 8:30 a.m. ET, as the train approached the 36th Street subway station in Brooklyn’s Sunset Park neighborhood, according to the New York City Police Department.

A man, who was seen mumbling to himself on the train, donned a gas mask and detonated a smoke canister commonly bought online before pulling out a .38-caliber handgun and opening fire, a police official told ABC News. He fired a barrage of at least 33 bullets, shooting 10 people, according to police. The gun jammed during the incident, which is believed to have saved lives, a law enforcement official told ABC News.

Smoke poured out of the subway car as the doors opened and screaming riders ran out onto the platform of the station. Bloodied people were seen lying on the floor of the train and the platform as others attempted to administer aid.

A total of 29 people were transported from the scene to local hospitals with various injuries. Five of the gunshot victims were critically injured and have since stabilized, a fire department official told ABC News. As of Wednesday morning, just four of the wounded remained hospitalized, according to Adams.

Police described the gunman, who is still on the run, as an “active shooter.”

“At this time, we still do not know the suspect’s motivation,” New York City Police Commissioner Keechant Sewell said at press conference Tuesday evening. “Clearly this individual boarded the train and was intent on violence.”

A senior federal law enforcement source told ABC News that authorities are concerned Tuesday’s shooting showed a level of planning and commitment to kill scores of commuters during rush hour. The New York City mayor said there was currently no evidence to suggest the gunman had any accomplices.

Police said the suspect, James, had rented a U-Haul van possibly connected to the violence. The key to the van and a credit card, which law enforcement sources told ABC News was used to rent a U-Haul, were among the gunman’s possessions recovered from the scene of the shooting. James had rented the same van in Philadelphia, according to police, who noted that investigators weren’t sure whether he had any link to the attack.

“We are endeavoring to locate him to determine his connection to the subway shooting, if any,” James Essig, the New York City Police Department’s Chief of Detectives, said at the press conference Tuesday evening.

Senior law enforcement officials told ABC News that they have uncovered a number of social media posts and videos tied to James and are studying them closely to see if they are relevant to the subway attack. In one video posted to YouTube just hours before Tuesday’s shooting, James appears to be driving a truck.

The New York City police commissioner said she increased security for the mayor after investigators found what she called “concerning posts,” but declined to call them “threats.”

“There are some postings possibly connected to our person of interest where he mentions homelessness, he mentions New York and he does mention Mayor Adams,” Sewell told reporters Tuesday evening. “And as a result of that, in an abundance of caution, we’re going to tighten the mayor’s security detail.”

Police said the U-Haul van was found on Tuesday afternoon, unoccupied and parked near a subway station on King’s Highway in Brooklyn’s Gravesend neighborhood, about 5 miles southeast of the 36th Street station. Nothing of investigative interest was discovered in the vehicle, apart from a pillow and other indications that James had been living inside, a law enforcement source told ABC News.

Other items discovered at the scene of the shooting include the Glock 9 mm semi-automatic handgun used in the attack, three extended magazines, a hatchet, gasoline, four smoke grenades and a bag of consumer-grade fireworks. The gun was not stolen, according to police. Investigators are sifting through evidence looking for any possible fingerprints on the gun and the other recovered items.

None of the surveillance cameras inside the 36th Street subway station were working at the time of Tuesday’s shooting, a police official told ABC News. The cameras, which are aimed at the turnstiles, didn’t transmit in real-time due to a glitch computer malfunction, a source said. The same glitch impacted cameras at the stops before and after 36th Street. Investigators said they are looking into how this malfunction happened.

However, the cameras at the Kings Highway subway station in Gravesend were transmitting live feeds in real-time. That’s where investigators believe James entered the subway on Tuesday morning, just blocks from where the U-Haul van was parked and eight subway stops away from 36th Street.

Police were able to get an image of the suspect from a bystander’s cellphone video, a law enforcement official told ABC News. Investigators are looking through video from other witnesses and surrounding businesses, hunting for any clues.

Service resumed at the 36th Street subway station in Sunset Park on Wednesday morning, after police concluded their investigation there.

The bloodshed comes amid a surge in crime within New York City’s transit system. The mayor said he has already doubled the number of police officers patrolling the city’s subway stations and is also considering installing special metal detectors in the wake of Tuesday’s shooting.

“There are many rivers that feed the sea of violence and we have to damn each one,” Adams told ABC News.

Anyone with information, videos or photos related to the shooting is urged to call NYPD Crime Stoppers at 1-800-577-TIPS.

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