Not 10 minutes into date night, Gabe Thomas and his girlfriend, Shirley Yu, found themselves crouched under their table at Birds of a Feather, a sleek Chinese restaurant in Williamsburg, Brooklyn, where a plate of pea shoots costs $21.

Just 20 feet away, a man wearing a mask brandished a gun in the crowded dining room and with a henchman grabbed two phones and a watch from three men at a table near the front door.

Diners dashed into the kitchen. Chairs toppled. Glasses shattered. A cacophony of screams filled the room.

The perpetrators quick-walked out and fled on a moped, leaving behind a half-empty dining room where a handful of unfired bullets had fallen to the floor. The stickup took less than 40 seconds.

The robbery in the heart of Williamsburg — a once-bohemian enclave in North Brooklyn now home to designer clothing stores and glassy towers — alarmed and unsettled both foodies and residents. And it was just one in a string of similar robberies in and around some of Brooklyn’s and Lower Manhattan’s most in-vogue establishments in the past month. In each case, the perpetrators have swiped luxury watches from diners, according to the police, including, in one episode, a timepiece worth $100,000.

Such crimes are unusual in the affluent neighborhoods that have been targeted, rare incursions of the city’s troubles into its glittering play spots. And they have lit up message boards, receiving the kind of outsize attention — and outrage — that everyday crimes in New York’s poorer neighborhoods often do not. The thefts have propelled persistent grousing that the city is slipping into lawlessness, a perception that no recitation of contrary statistics has dispelled.

The robberies follow the same pattern: Two men, one carrying a gun, steal belongings from restaurant patrons before fleeing, often via moped or dirt bike, according to interviews and surveillance footage. Most of the robberies have happened between 6:30 p.m. and 9:30 p.m. and have targeted restaurants that attract celebrities and Brooklyn’s young creative types.

Marlow and Sons, an oyster bar just 10 minutes from Birds of a Feather, was hit in the early evening on May 31. A man approached a 38-year-old man and a 40-year-old man outside the restaurant with a gun and demanded their watches, the police said. He took a Rolex and an Audemars Piguet, worth $40,000 collectively, before fleeing on a “two-wheeled vehicle” with another person, the authorities said.

About three weeks later, a similar heist was reported outside Carbone, an Italian restaurant in Greenwich Village with a dress code — “any guest who does not appear sufficiently well-presented may be refused entry” — and an exclusive reservation list. There, two men robbed a 39-year-old man of his $100,000 Patek Philippe watch at gunpoint, the police said.

The theft at Birds of a Feather took place three days later, the only one of the recent robberies to occur inside a dining room. Then, late last Thursday, the police said that two people riding a moped and carrying a gun stole a watch and a purse from a 29-year-old man and 32-year-old woman on the corner of Manhattan and Norman Avenues in Greenpoint, a Brooklyn neighborhood just north of Williamsburg. The pair was en route from Twins Lounge, a popular spot nearby, to another cocktail bar down the street, according to Greenpointers, a local news website.

No arrests have been made in any of the robberies, the police said. The Police Department did not say whether the four similar thefts were connected.

“We haven’t had crime like this penetrate the neighborhood in a very long time,” said Allyson Stone, a board member for the North Brooklyn Chamber of Commerce, who attributed the trend to the area’s relative wealth. The median household income in Williamsburg and Greenpoint in 2022 was $98,750, about 27 percent higher than the citywide median, data from the Furman Center at New York University shows.

The crimes have put North Brooklyn on high alert, according to residents and business owners.

“It did surprise me in a neighborhood like Williamsburg,” said Mr. Thomas, who witnessed the Birds of a Feather robbery. It’s a “higher income, more gentrified neighborhood,” he said. Local residents “have an expectation that, like, that kind of stuff doesn’t happen.”

But thefts of luxury watches are not a new occurrence in major cities like New York. After the coronavirus pandemic, police departments reported a sharp rise in thefts of luxury watches, which are light and difficult to trace and therefore ideal targets.

Sean Wilson, 28, who witnessed the robbery at Marlow and Sons while dining nearby with his fiancée, said that they have begun dining earlier and leaving their valuables, including her diamond ring, at home. “I don’t think that was a thought that I’ve ever really had,” he said.

Robberies in New York City so far this year have risen 4.9 percent from the same period last year, according to the Police Department. In the 90th Precinct, which includes Marlow and Sons and Birds of a Feather, robberies are up 11.2 percent.

Yiming Wang, who owns Birds of a Feather with her husband, Xian Zhang, said they were taking safety precautions after the theft, including upgrading the restaurant’s surveillance system and supporting their employees, some of whom were injured during the commotion. Ms. Wang said they even considered hiring a security guard.

Major Food Group, which owns Carbone, did not immediately respond to a request for comment. A representative from Marlow and Sons declined to comment.

But Andrew Rigie, the executive director of the New York City Hospitality Alliance, said that though the string of robberies had sparked concern, that was no reason for New Yorkers to stop dining out.

“There’s more than 25,000 restaurants across the city of New York with millions of people eating out all the time without incident,” he said. “People should not be worried about going out to eat.”

On a recent humid evening at Carbone, a stream of women in slinky dresses filtered into the candlelit restaurant with their male counterparts. Inside the outdoor dining shed, patrons clinked wine glasses over white tablecloths.

Ryan Elberg, 41, said that as someone who enjoys nice watches, he was concerned when he first heard about the robbery, but it hadn’t deterred him. “I figured lightning doesn’t strike the same place twice,” he said. After reflecting, he added: “Get insurance on your watch,” punctuating his advice with an expletive.

Nick Khera, 40, in town from Miami, heard about the robbery at dinner that night. A fellow customer had warned him to wait inside the restaurant until his ride was ready, and after dinner he rushed to a waiting car.

Across the bridge in Williamsburg, dinner rush at Birds of a Feather was in full swing. Customers, many clad in linen, sipped beers and slurped dumplings near the restaurant’s large glass windows.

Steve Zofcin, 33, a 13-year neighborhood resident who was walking by with friends, said he thought the robbery had received more attention than it deserved because it happened in a predominantly white neighborhood.

“That’s just part of living in a city,” he said. “You’re more likely to get bit by a person in New York than a shark.”