Two construction workers were hurt when part of a building under construction collapsed in Mott Haven on Tuesday afternoon, according to the city Department of Buildings.

The collapse happened shortly before 2 p.m. at 477 Willis Ave., where crews were working to expand a vacant one-story building into two stories.

Buildings inspectors said workers were doing masonry work on a stairway when a joist on the second floor collapsed into the cellar.

Police initially reported that bricks fell from a wall and caused scaffolding to collapse.

A 28-year-old woman and a 20-year-old man working at the site were taken to Lincoln Hospital with minor injuries.

One witness said the workers were covered in dust but appeared to be alive when rescuers took them away.

“They looked yellowish because they were completely covered in dust, but they were alive, and that’s what matters,” the witness said. “They were taken to the hospital. Thank God.”

The Fire Department responded to the scene. The city’s Department of Buildings and Emergency Management were notified, along with the federal Occupational Safety and Health Administration.

After inspecting the site, the Buildings Department found several safety problems. Inspectors said there was no site safety plan or required worker safety meeting. They also found improperly maintained scaffolding, an inadequate exit and no overhead protection for a neighboring property.

The contractor also failed to notify the Buildings Department about excavation work, according to inspectors.

The city issued a full stop-work order, meaning no construction can continue for now.

Before work can resume, the contractor must fix all the violations and submit a report explaining how workers and nearby properties will be protected moving forward.