Earlier, the FDNY said several construction workers were being transported to the hospital for treatment, and firefighters were trying to get a count of all the workers on the job site. Excavation work had been underway at the construction site, which has been approved for a three-story building, officials said. Plans for a nine-story, mixed-use building there had yet to be approved, officials said.

A stop work order has been issued for the neighboring construction site as search and rescue continues, according to the Department of Buildings (DOB). The cause of the collapse remains under investigation by the DOB and law enforcement, authorities said. "We will find out what happened, and we will share that information with New Yorkers," Mamdani said Thursday.

The DOB said its inspectors were at the scene on Thursday assisting first responders with recovery efforts and conducting structural stability inspections of nearby buildings. In March, the DOB said it issued a stop-work order for the construction site, at 2625 Bedford Ave., after inspectors found demolition was underway without adequate overhead protection installed for the neighboring properties.

During a follow-up in April, the DOB said it found that demolition work had resumed in violation of the active stop-work order, resulting in another violation. The order was lifted in May after the project team corrected all the violations, according to the DOB. Mamdani said Thursday that five entities are involved with the construction site and are associated with approximately 100 other sites across New York City.

"Our Department of Buildings is commencing sweeps of those sites today," he said. Vacate orders are in place for three buildings closest to the incident, located at 1323, 1325 and 1327 Flatbush Ave., Mamdani said.