What to Know About the Deadly Building Collapse in Brooklyn

A three-story apartment building collapsed and largely fell into an adjacent construction site in the Flatbush neighborhood of Brooklyn on Wednesday, killing at least eight people and injuring 18 others, Mayor Zohran Mamdani said.

Just before 4 p.m. on Thursday, after sifting through the debris for nearly 24 hours amid heavy rain, rescue workers announced that they had concluded their search efforts and that there were no more victims.

The site was turned over to the Police Department and the city’s Department of Buildings, which are investigating the cause of the collapse.

“This has been a devastating evening and morning for our city,” Mr. Mamdani said at a news conference on Thursday afternoon. “We are mourning too many people who we love.”

The collapse occurred while an excavation was taking place at the adjacent construction site on Bedford Avenue, where the city had approved plans for a three-story building.

What happened?

At 4:01 p.m. on Wednesday, the Fire Department received a 911 call about a building collapse at 1321 Flatbush Avenue, Mr. Mamdani said at a news conference later that day.

Canine units, drones, helicopters and fire trucks were used in the search, alongside excavation machinery, in a search and rescue operation that continued into Thursday. The adjoining wall of an adjacent building was sheared off by the collapse, leaving a staircase, a bedroom and closets exposed to the open air.

Why did the building collapse?

It’s not clear yet. The Department of Buildings said that its engineers were conducting structural stability inspections of nearby buildings, but city records suggested that there had been at least some concern about the condition of the collapsed building.

The building that collapsed was built in 1930 and had four apartments, according to city records. It is in the Little Haiti section of Flatbush, on an avenue lined with shops.

The Department of Buildings said the developers of the adjacent construction site had an active permit for excavation and foundation work. The agency’s commissioner, Ahmed Tigani, told reporters that workers were excavating that site at the time of the collapse.

According to city records, an inspection related to the construction site and filed with the Buildings Department in March noted that the north facade of the collapsed building was in “poor condition with noticeable cracks,” but construction appears to have continued nonetheless.

A complaint filed with the Department of Buildings on Wednesday night, after the building collapse, also raised concerns about the excavation work at the adjacent development site, 2625 Bedford Avenue.

The anonymous complainant said that the “subcontractor may have excavated too much of the area along the neighboring foundation” on a site with sandy soil and high groundwater. It is unclear who submitted the report. The Buildings Department said it was investigating it.

On Thursday, Mr. Mamdani said that he was “incredibly troubled” to hear that work had gone on despite the warnings. A full stop-work order has been issued for the construction site, the Buildings Department said.

What do we know about the victims and the rescue effort?

The authorities have not officially released the names of the victims, but Mr. Mamdani confirmed that six adults and two children had died in the collapse.

The dead included elementary-school-age cousins, construction workers from Ecuador and Guatemala, and a young man from Guinea in West Africa, according to an internal police report and the family and friends of the victims.

Six of the victims died when the building crashed down at around 4 p.m. on Wednesday, while two others succumbed to their injuries after they were taken to nearby hospitals, the mayor said.

The names of seven of the dead are: Nicole Daniela Salvala Rodriguez, 9; Kevin Santiago Reyes Gonzalez, 10; Gabriel Siguencia, 22; Mamadou Bhoye Barry, 23; Edgar Santiago Sapón Gutierrez, 26; José Luis Caguana, 26; and Juan Daniel Salvada Guzman, 31.

A man believed to be between the ages of 30 and 35, whose remains have not been identified, was also killed.

Eighteen people were also injured in the collapse, including four firefighters, and at least one of the injured was in critical condition on Thursday.

Flatbush is home to a large number of immigrants. After the collapse, some onlookers said they saw emergency responders pull a toddler from the rubble. On Wednesday, a woman who is six months pregnant and whose husband had been searching for her, was lifted from a pit and brought to a hospital.

Emergency responders conducted search and rescue operations overnight on Wednesday and well into Thursday afternoon, even as a heavy rainstorm left shin-high pools of water, complicating the search operation.

At 3:37 p.m. on Thursday, the Fire Department announced that it had concluded its rescue efforts.

What happens now?

Mr. Mamdani said the city had begun to investigate the disaster, with an additional focus on the construction site. The Buildings Department has identified “five entities” associated with the project, and city officials plan to conduct sweeps of 100 other sites the groups are involved with to ensure they are safe.

“If there is anyone or any entity operating in this city that bears responsibility for what happened, we will hold them fully accountable,” Mr. Mamdani said.

Many residents near the site of the collapse remained indefinitely displaced on Thursday, though some farther south on Flatbush Avenue had returned to their homes. The city’s emergency management agency and the American Red Cross have opened a reception center for affected and displaced residents at the Flatbush Y.M.C.A., at 1401 Flatbush Avenue.

The authorities encouraged people who are unable to reach someone they believe to be affected by the collapse to call 311. People outside the city can call 212-639-9675.

Sharon Otterman, Max Bearak, Caitlyn Freeman, Ishani Desai, Sarah Chatta, Mihir Zaveri, Troy Closson, Ana Ley and Emma G. Fitzsimmons contributed reporting.