(NEW YORK) — New York City police are still hunting on Wednesday morning for a gunman who opened fire on a rush-hour subway train in Brooklyn.

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.

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. The bloodshed comes amid a surge in crime on New York City’s transit system.

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 source said it is too early to know if the suspect acted alone.

Police said they are also looking for the renter of a U-Haul van possibly connected to the violence. Frank R. James, 62, has been identified by police as “a person of interest in this investigation” and there’s a $50,000 reward for information leading to his whereabouts.

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.

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. Investigators are working to determine if the U-Haul van has any connection to the suspect and are asking the public for their help with any information on what might have happened between the location where the vehicle was parked and the eight subway stops to 36th Street.

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 are looking into how this malfunction happened.

Nevertheless, 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 that point to a suspect.

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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