The collapse of a crane at an Upper East Side construction site on Friday morning killed two workers and severely damaged several high-rise apartments. And it left many New Yorkers pondering an unsettling question: This again?

It was the second time in two months that a familiar urban fear came to stunning fruition: a similar incident in March killed seven people and prompted officials to enact more stringent safety regulations and assure the public that they should not be afraid of construction sites around the city.

But Friday’s deadly accident has turned up the debate among citizens and politicians about whether the city acted forcefully enough to address those concerns  and whether New Yorkers still felt unsafe.

Image A rescue dog was used to search for victims of the crane collapse at 91st Street and First Avenue. Credit... Todd Heisler/The New York Times

"I always look up at that crane,” said Linda Taylor, 49, a traffic officer who worked in the neighborhood near the site of Friday’s collapse. She said she had developed a habit of checking the crane, especially after the incident in March. “I’m afraid to drive under it,” she said.

The city could not immediately account for the cause of the collapse, which occurred moments after 8 a.m. at a construction site at the corner of 91st Street and First Avenue.

Witnesses said the horizontal, unloaded arm of the crane began to circle and then snapped off, propelling the cab and the upper portion of the arm onto a white-brick residential building across the street. The cab demolished part of a top-floor penthouse and then plunged down the north facade, shearing off balconies and leaving a trail of pockmarks in the brick.

Image The wreckage of the crane at the intersection of 91st Street and First Avenue. Credit... Tina Fineberg for The New York Times

The operator of the crane, Donald Leo, 30, of Staten Island, was sitting in the cab as the structure fell. He was pulled from the wreckage by rescue workers and pronounced dead at the scene. A second man, Ramadan Kurtaj, 27, of the Bronx, was also killed.

No one in the building was injured, and one pedestrian was treated for a minor injury and released, according to the mayor.

The collapse occurred just two days after the city relaxed some of the rules it had put in place after the March accident. Instead of requiring inspectors to be on hand at construction sites when a crane is erected or made taller, the Buildings Department said on Wednesday that it would switch to a system of spot checks and “safety meetings” where workers would be briefed on proper procedures.