Part of the scaffolding at the World Trade Center site fell Thursday, injuring two firefighters.
The demolition work on the former Deutsche Bank skyscraper had been suspended after Saturday's fire, but workers on Thursday were still busy removing toxic debris from its remaining 26 stories.
Shortly before 2 p.m., the two firefighters were hit by the falling material.
Fire Department spokesman Frank Gribbon said scaffolding fell from the side of the building facing the World Trade Center site, leaving the two firefighters hospitalized in stable condition, one with a head injury. Initial reports that some construction workers also were injured could not immediately be confirmed.
City officials gave a different scenario, saying that a piece of equipment, not collapsing scaffolding, fell from a high floor of the building and through a sidewalk shed, injuring the firefighters who were standing beneath it.
Fire marshals have been at the partially demolished building this week investigating the cause of the fire.
On Wednesday, city officials acknowledged that the fire department had not regularly inspected the building, which has been vacant since it was damaged by the falling twin towers during the Sept. 11, 2001, terrorist attacks. They also did not have a plan to fight a fire there, two steps that were required, the city said.
When the fire broke out, the pipe needed to bring water up to the level of the fire was not working.
Two firefighters became trapped on one of the burning floors and died of cardiac arrest and smoke inhalation after their oxygen ran out.
The Fire Department had not inspected the pipe since April 2006, although it was required to do so every 15 days, the city said in a statement. The head of the city's fire union said the Fire Department had told the local firehouse over a year ago to stop the inspections because of health concerns in the toxic building.
Also this week, the main contractor taking down the building was dropped from the job. Project manager Bovis Lend Lease sent a default notice Wednesday to John Galt Corp., giving Galt five days' notice before it could terminate the contract.
Galt had been cited with dozens of safety violations, including one after a 15-foot (6.8-kilogram) pipe fell 35 stories through the roof of the local firehouse in May. The company also was cited early this month after torch work sent burning sparks down through the building.
Messages left for Galt, which has about 200 workers on the project, weren't immediately returned.
The 41-story building was being dismantled floor by floor, a dangerous process because it is contaminated with asbestos and other toxins.