New York City was already on edge about rising gun violence, lawlessness and hate crimes. Then came Tuesday’s attack on a Brooklyn subway, in which a masked suspect detonated two smoke grenades and shot 10 people during the morning rush hour.

On Wednesday, police arrested Frank James, a 62-year-old man who had earlier been named as a suspect in the shooting, in Manhattan’s East Village.

The precise motives for the attack remained unknown. But it appeared calculated to unnerve a city where public safety has become an overriding concern for residents and businesses struggling to recover from the coronavirus pandemic.

It occurred on the subway, an essential means of transit for the city’s workers but also, increasingly, a warren of homelessness, mental illness and senseless violence. Eric Adams, the city’s new mayor, who began his career as a transit cop, has made tackling crime and safety on the subway in particular one of his top priorities.

In a sign of the city’s overlapping crises, Adams could not visit the crime scene on Tuesday because he was quarantining with Covid-19. He recorded a statement in which he vowed: “We will not allow New Yorkers to be terrorised, even by a single individual.”

Adding to the menace, the attack took place in a Brooklyn neighbourhood with a large Asian-American community, whose ranks have suffered a disproportionate burden of hate crimes of late. Many are traumatised by the February murder of Christina Yuna Lee, a woman who was stabbed more than 40 times by a homeless intruder after returning from a night out.

In its capacity to arouse shock and horror, Tuesday’s attack transcended boundaries between New Yorkers.

“I don’t feel safe any more. I carry pepper spray with me because that’s all I can do,” said Maria Keller, who works at the UMK Brooklyn Grocery on Fourth Avenue and 35th Street, half a block from the shooting.

Keller has lived in the city since 1984 and said lately “the city feels like back in the 80s. I don’t go on the subway any more, maybe once a month. When [Mayors Rudy] Giuliani and [Michael] Bloomberg were in charge they did a good job. I felt like I could go on the subway and even fall asleep. But now it’s too dangerous.”

In the aftermath, politicians who have grown practised in recent months at public denouncements of violence appeared more emphatic and emotional than usual.

“No more mass shootings. No more disrupting lives. No more creating heartbreak for people just trying to live their lives as normal New Yorkers. It has to end, it ends now,” said Kathy Hochul, the governor of New York.

Jumaane Williams, the city’s public advocate, noted that one of his associates was on the train when the attack occurred. “It’s not even summer yet and we’re dealing with this violence,” he said, in an acknowledgment that New York’s shootings tend to increase as the temperature rises.

As with other big US cities, there were mass protests in New York two years ago following the police murder in Minneapolis of George Floyd. The state legislature also implemented criminal justice reforms intended to reduce the prison population.

Now the political winds appear to be shifting, or at least moderating. New Yorkers in November elected Adams, a former police captain whose promise to contain crime was the cornerstone of his campaign. He has since sent controversial anti-crime units back into the streets to crack down on the gun trade, including a proliferation of difficult-to-trace “ghost” guns. He has also restored some of the aggressive “broken windows” policing strategies popularised by Giuliani in the 1990s.

Crime remains well below levels from generations past. Last year, the city recorded 485 murders compared with 2,262 in 1990.

Since the pandemic, though, the trends have headed in the wrong direction. Shootings are up 8 per cent this year, according to the NYPD, and more than 72 per cent from two years ago.

The subway has been a particular focus of concern. It has featured deadly hate crimes, in which Asian-Americans have been assaulted and even pushed on to the tracks.

Like Keller, the grocery store worker, many New Yorkers are staying away. In a recent week, ridership was only about 56 to 58 per cent of pre-pandemic levels, according to Metropolitan Transportation Authority statistics.

Some business leaders now view the subway — not Covid — as the biggest obstacle to convincing their employees to return to the office, threatening the post-pandemic livelihood of the city itself.

A recent survey of 9,400 Manhattan office workers conducted by the Partnership for New York City, a group of business executives, found more than 80 per cent relied on public transit to commute to work, and that public safety, more than health, was their overriding concern.

“Every New Yorker can identify with those that were caught in the subway car with the shooter,” said Kathryn Wylde, the partnership’s president. “This is getting people at a moment of high anxiety and that will magnify the reaction.”

Richard Aborn, a lawyer who is president of the Citizens Crime Commission, a non-profit focused on public safety, was reluctant to draw conclusions.

“What we do know is that this will greatly increase the sense of insecurity on the subway, at the very moment city officials are doing so much to try and get people back on the system,” he said. Aborn called the assault “the type of random attack that sows fear citywide”.

In Sunset Park, the diverse working-class neighbourhood where the attack occurred, a cross-section of business owners and local residents said they had all noticed a rise in homelessness and erratic behaviour in recent years.

“You see more homeless and odd people around, and you just never know if they’re going to snap,” said Tony Tan, half of the pair behind Jack & Tony’s Auto Repair shop on Fourth Avenue, just north of the attack.

Josh Tyler, a 20-year-old resident of the Midwood section of Brooklyn, said he adopted two pit bulls last year to protect his mother at their home when he is not around.

“At this point you have to,” Tyler replied, when asked if he planned to change his behaviour in light of Tuesday’s attack. “You don’t know what [the shooter] has with him, you don’t know what people he’s got around him. If you’re throwing smoke in the subway, you’re trying to cause chaos.”