Federal workplace-safety regulators are investigating an incident at a construction site near Rittenhouse Square that left one worker dead.

So far, few specifics are known about the Wednesday fatality near Sansom and South 24th streets, where five luxury homes are being built by developers Bernier Real Estate Group and OCF Realty. According to Philadelphia Police Department, a construction worker fell and was pronounced dead around 11:40 a.m.

On Thursday, the Philadelphia Medical Examiner’s Office identified the worker as Siarhei Marhunou, a former resident of Grodno, Belarus, who has resided in Philadelphia for two years. According to a GoFundMe launched by his wife, Marhunou leaves behind a three-month-old child. The Inquirer was not immediately able to reach Marhunou’s widow.

Ori Feibush, president of OCF, said he arrived at thesite shortly after he learned about the accident. He said he was waiting to learn more about the circumstances of the death, which is now being investigated by the federal Occupational Safety and Health Administration.

“It’s hard to know what could have prevented this without knowing what exactly unfolded,” said Feibush, who said this is the first worker death at on OCF project. The Inquirer couldn’t immediately confirm that through OSHA’s fatality database, which lists only the direct employers of the deceased.

According to an OSHA spokesperson, Marhunou was employed by a company called DBCI LLC. DBCI had been subcontracted to work on the project by the Huntingdon Valley-based construction company Hammers Contractors. Hammers had, in turn, been contracted by the Fitler Construction Group, which was managing construction for OCF.

It’s unclear what work DBCI LLC was doing on the project when the death occurred, how they were hired, or where the company is headquartered.

Feibush said he was not aware Hammers Contractors, a subcontractor the developer had worked with on dozens of projects and described as “consummate professionals,” had hired DBCI. OCF does not allow subcontractors to hire other businesses for additional work, he said.

Hammers Contractors directed inquiries to DBCI, though it couldn’t offer a contact, and later asserted the company didn’t know anything about the incident. Efforts to find a working number for DBCI were unsuccessful.

OSHA has six months to complete a probe and release its findings. Feibush said his company and its subcontractors on site Wednesday were cooperating with federal investigators.