A construction worker was killed at a Brooklyn work site after falling four stories from scaffolding Friday morning, police said.

The hard hat identified as, Wilfredo Enriques, 59, was on the hanging scaffold working on the under-construction building at 325 Kent Avenue in Williamsburg at around 8:05 a.m. when he took the fatal plunge, officials said.

Emergency responders rushed the Enriques, a Brooklyn resident, to Woodhull Hospital where he died.

A worker at the scene said that the victim’s safety harness was not fastened.

“He wasn’t strapped in,” the worker said.

The mixed-use building, 325 Kent Avenue located between South 3rd and 4th streets, is part of the Domino Sugar Factory redevelopment by Two Trees Management. The actual site of the former Domino Sugar Factory is across the street.

Enriques was an employee for PG Products of New York, a subcontractor in charge of installing the façade and windows at the job site, Two Trees said.

John Gibney, the CEO of the company, called Enriques “a dedicated employee and friend for the past decade.”

“We are fully cooperating with Two Trees and the DOB to understand how this tragedy occurred,” Gibney said.

Gary LaBarbera, president of the Building and Construction Trades Council of Greater New York, said in a statement, “Once again we mourn the loss of a construction worker, who perished this morning at the Domino Sugar Factory project in Brooklyn.”

“We offer our deepest condolences to his family and loved ones at this difficult time,” LaBarbera said.

He noted, “Incidents like today’s, which are preventable, happen all too often and underscore the need for the Mayor, the City Council and the Department of Buildings to work together to enact greater site safety regulations and mandatory safety training and apprenticeship programs.”

The Department of Buildings is investigating the incident.