This post has been updated.

Two teenagers are in custody in connection with the shooting of a man on a Green Line train, who was found on the Anacostia Metro station platform Tuesday afternoon, police said.  The alleged shooter is 16 and police are seeking to have him tried as an adult, authorities said Tuesday night.

Both will be charged with assault with intent to kill, police said.

Metro spokesman Dan Stessel said surveillance technology helped police quickly apprehend the two suspects, the other of whom is 19.

Metro Transit Police identified the 19-year-old as Andre Broadie of Northeast Washington. The second suspect is 16 years old, not 15, as was previously reported by transit police. He initially provided false information, police said.

A Metro train car that is part of the investigation into a shooting that wounded a 24-year-old man Tuesday afternoon. (Faiz Siddiqui/The Washington Post)

D.C. Police spokesman Dustin Sternbeck said the 24-year-old victim was shot on a Green Line train as it approached the Anacostia Metro station and that he was found on the platform about 12:45 p.m. The man was hospitalized in stable condition late Tuesday, police said.

Police had no immediate information on the motive.

Metro Transit Police Chief Ronald A. Pavlik Jr. said this was the only instance he could remember in the past 20 years in which someone fired a gun while on board a Metro train. “This was a truly anomaly event,” he said.

Stessel said multiple witnesses remained at the scene after the shooting and assisted D.C. police in identifying the suspects in person.

Metropolitan Police Department officers obtained video of the suspects on the train and shared it with officers by email rapidly after the shooting, Stessel said. That video was what led officers to recognize the suspects when they saw them. Sternbeck said the two were spotted by a D.C. police officer as they walked across the South Capitol Street Bridge, away from the station.

The 16-year-old allegedly fired one shot, striking the victim. There were other people on board the train, but it was not packed, Stessel said.

Detectives began their investigation of the train while it was at the station. It was then moved to a railyard where the investigation will continue, Stessel said. Metro Transit Police department is the lead agency in the investigation.

Authorities at the Anacostia Metro station where they are investigating the shooting of a man on a Green Line train Tuesday afternoon. (Faiz Siddiqui/The Washington Post)

In response to a question about the presence of police officers on trains, Pavlik said one officer was at the bus bay at the Anacostia station, though not on the train, when the shooting happened.

The shooting was the latest in a series of recent high-profile assaults in the transit system involving teenagers.

Earlier this month, six Wilson High School students were arrested in connection with a morning rush-hour fight at Gallery Place, in which a teenager allegedly punched a 35-year-old man getting off a train. Surveillance footage shows the man being slammed to the ground before the teens rush onto the train.

In December, a man suffered a concussion and broken jaw after he was assaulted by youths aboard a Red Line train between Union Station and NoMa-Gallaudet University during the evening rush hour.

And Monday, a 61-year-old visually-impaired woman was swarmed by a group of teen girls and robbed of her purse as she got off a Metrobus. A bus driver came to her aid and pursued the attackers into the L’Enfant Plaza Metro station where two of the girls — one 15 and one 16 — were arrested by Metro Transit Police and charged with robbery.

“It’s always concerning whenever you see kids commit criminal activity,” Pavlik said. “I don’t truly know what the role of the juvenile was at this point in time,” he said referring to the 16-year-old suspect in Tuesday’s shooting.

“Hopefully we’ll get to what caused it — is it a neighborhood beef or an ongoing thing — and that will come out through the interviews,” he said.

Describing gunfire on a train as highly unusual and perhaps unprecedented in Metro’s history, Stessel said that riders will not see an increased police presence on trains as a result of the shooting.

“There will be no change in our patrol strategy because of [Tuesday’s] incident,” he said, noting that police officers, as a rule, are deployed based on crime trends, not single incidents.

Stessel said it is generally more efficient for officers to be posted on station platforms and mezzanines, because that allows them to see an entire train and move quickly from one station to another in an emergency.

However, in recent weeks, Stessel said, more officers than normal have been riding on trains because of an uptick in robberies and assaults on trains, mostly by groups of juveniles. That level of deployment will continue, he said, but not as a result of Tuesday’s shooting.

Riders at the Anacostia were shaken following Tuesday’s shooting. The huddle of police officers Tracey Cobb observed was a stark difference from what she usually sees on weekday afternoons, she said as she waited to board a train toward Greenbelt.

“Of course you see the visibility of officers when this happens,” Cobb, 50, said. “We need to see them when things are not happening.”

Cobb, who has a disability and uses a cane, said shes often sees groups of teenagers acting up on the rail system during weekday afternoons. Her disability leaves her feeling vulnerable to an attack, she said.

“Sometimes you just don’t feel safe,” she said. “You see kids get on in a mob and terrorize people. Just terrorize them.”

Joseph Fortune, 26, said he would like to see more officers on platforms “particularly to make senior citizens feel safe.”

Others said it wasn’t unusual to hear of violence near bus bays and Metro stations, but a shooting on board a train was shocking.

“It was just unbelievable,” said Luemeishia Judge, 40, of Southeast Washington. Judge, whose children are 13 and 14, said she often allows them to ride Metro alone, but Tuesday’s violence had her reconsidering.

“Maybe I’ll keep them home for a while,” she said.

Paul Duggan contributed to this report.