The gunman double-parked outside the tower at 345 Park Avenue, strode into the lobby with a cheap AR-15-style rifle, and killed three people, including an off-duty police officer. He took an elevator to the 33rd floor and fatally shot a final victim before turning the gun on himself. The episode was over in minutes.
Despite New York’s stringent gun laws and the office building’s tight security, law enforcement officials and legal experts said, the shooting — the deadliest in New York City in 25 years — may have been all but unstoppable.
New York has one of the world’s most sophisticated surveillance networks and the resources to deploy a massive police response, said Brittney Blair, an associate managing director of K2 Integrity, a risk-management and investigative firm.
But a piecemeal network of looser regulations nationwide enabled a lone gunman with no criminal history to drive undetected across several states on his way to the city.
“It feels impossible to stop something like this,” Ms. Blair said.
The attack underscores the limits that even a dense web of gun safety laws and private security precautions can have in a country flooded with inexpensive weapons. Beginning last week, the gunman, Shane Devon Tamura, 27, who lived in Nevada, drove through several states, including Colorado, Nebraska, Iowa and New Jersey, before arriving in Midtown Manhattan, his BMW filled with ammunition.
Mr. Tamura could have secured a semiautomatic rifle in a single day in Nevada, where he could bypass additional background checks, because he had a permit to carry a concealed weapon, said Nick Suplina, a senior vice president at Everytown for Gun Safety, a national gun violence prevention group. A federal ban on assault rifles ended in 2004; Mr. Tamura could have purchased the weapon for less than $500.
The police in New York began receiving 911 calls at 6:28 pm on Monday with reports of an active shooter. By then, Mr. Tamura had already left the vehicle between 51st and 52nd Streets and walked into the building, a police spokesman said. He turned right and shot the police officer, Didarul Islam, 36, who died in the lobby.
Mr. Tamura kept firing. He shot and killed Wesley LePatner, 43, who had ducked behind a pillar, and then, as he made his way to an elevator bank, killed Aland Etienne, 46, an unarmed security guard who was taking cover behind a front desk. After wounding another victim, Mr. Tamura summoned the elevator.
For unknown reasons, he spared the life of a woman who stepped out of the elevator into the lobby. He rode to the 33rd floor — the office of Rudin Management, a real estate firm that owns the Park Avenue building. He began to walk around the floor firing rounds, and killed his final victim, Julia Hyman, who worked at Rudin. He then turned down a hallway, pointed the gun at his own chest and fired.
The police were still investigating the motive for the attack. Mr. Tamura was found with a note urging the authorities to scan him for C.T.E., a degenerative brain disease caused by repeated head trauma that can be definitively diagnosed only after death.
The attack came as shootings in New York are close to record lows.
Through last week, there were 406 shootings reported in the city, down more than 21 percent from the same period last year and the lowest rate since at least 1993, according to an analysis of police statistics by Vital City, a civic think tank.
But the mass shooting on Monday represents a different sort of crime, one for which it would have been difficult for New York to prepare, said Elizabeth Glazer, Vital City’s founder and a former criminal justice adviser to Mayor Bill de Blasio.
“Once somebody has a gun and is determined to do what this guy did, unless you turn the city into an armed camp — and even then it’s a question — it is very hard to stop them,” Ms. Glazer said.
In 2022, the Supreme Court struck down a century-old New York law that had been widely considered one of the strictest in the country. But the state quickly put a new law in place that has so far stood up to legal challenges, keeping New York one of the least gun-friendly states in the nation.
David Pucino, the legal director of Giffords Law Center, a gun safety group, said Mr. Tamura would almost certainly have been unable to legally obtain a gun or a permit for it in New York.
Under New York’s SAFE Act, he would not have been able to buy his gun — a cheaply built AR-15 sometimes referred to as a “Reddit Special” for its popularity on the internet message board. New York law also would have prevented him from acquiring the concealed-carry permit he obtained on the other side of the country.
In New York, Mr. Pucino said, “He should have been arrested the second he stepped out of that car.” Had he been in Nevada, “he would have been legal until the second he opened fire.”
In a statement, Gov. Kathy Hochul of New York said the state has some of the strongest gun laws in the nation, but that local laws cannot make up for lax regulation elsewhere.
“We banned assault weapons,” she said. “But our laws only go so far when an AR-15 can be obtained in a state with weak gun laws and brought into New York to commit mass murder.”
Maureen Farrell and Thomas Gibbons-Neff contributed reporting.