A crane dropped a load of metal beams at the World Trade Center site, damaging a construction vehicle, the fire department said.
Tishman said a cable on the crane snapped at around 10 a.m. The truck had hauled the steel into the lower Manhattan site.
No one was in the truck when it was hit on Thursday.
The FDNY says one person was checked out by medical workers at the scene, but there were no serious injuries.
Preliminary reports indicate that the crane was removing the beams from the truck when a cable snapped. It's not clear how high the load had been lifted before it dropped, but workers at the scene said it fell from somewhere between 35 and 50th floors.
Construction worker Frank Pensabene said he heard a loud crash.
"Everybody was yelling and running," he said.
There were some subway disruptions for about an hour.
Tishman says it is investigating the matter along with the fire and buildings departments, and the Port Authority, which owns the site.
With reporting by Tracie Hunte and the Associated Press