Video posted to social media showed the top of the crane revolving in a full circle in rainy weather at the building, which has topped out at over 1,400 feet, on West 57th Street in Manhattan.
Fire officials said they started operations at the building shortly before 7 p.m. The Buildings Department sent inspectors. Traffic was shut down in the area, and subway trains were rerouted.
The crane is stable and is being evaluated, Buildings Department spokesperson Andrew Rudansky said in an email. The crane is designed to spin in the wind, he said, but inspectors are trying to determine what caused debris to fall.
There were no official details on what the debris consisted of.
The skyscraper was developed by JDS Construction Group. A message was left with the company.