Videos Show an Ordinary New York Morning Erupting Into Chaos on the N Train

Disruptions continued throughout the day: Several lines were shut down or running with delays, complicating people’s commutes. At the Atlantic Avenue-Barclays stop in Brooklyn, several M.T.A. workers stood by entrances to the subway, fielding anxious questions from passengers about alternative routes.

On Tuesday, Marjorie Michele, 50, a nursing technician from Ocean Hill, Brooklyn, took an Uber home from work, she said. Lines were still snarled from the attack, and it felt safer.

“It could have been me, it could have been any of my children,” Ms. Michele said. “Imagine those poor people who got shot this morning, they woke up this morning just to get wherever they were going.”

The day’s trauma would echo far beyond the train car in which the attack occurred, said Jaclyn Schildkraut, an associate professor of criminal justice at the State University of New York at Oswego, who studies mass shootings.

“In a mass shooting, there is a lot of attention focused on people who are killed or who are injured, and rightfully so,” she said. “But you had a train full of people who may not have been physically injured but who are going to bear traumatic injuries, and you have an entire city that is part of a bustling metropolis, that is now questioning their safety.”

Mayor Eric Adams had vowed to crack down on subway violence, and the shooting came amid what was already an increased police presence. A few weeks after a woman was pushed to her death in front of a train in mid-January and a homeless man was charged with her murder, Mr. Adams announced plans to stop homeless people from sheltering on trains and platforms and to have the police evict people who are not using the trains for transportation.

The shooting threatens the slow return riders had begun to make to the subway. Its fiscal health has been seen by officials as linked to the aboveground economy of Manhattan, particularly its business districts. Ensuring a safe subway system has been part of a strategy to lure people back to offices, and tourists back to the city.