NBC New York reports that the two workers have been secured using ropes, and emergency workers are trying to find a way of winching them to safety.
Parts of the streets below, on 57th and 58th streets and Eighth Avenue, have been closed off.
More top news
Another mild night
Tracey Crouch says she hopes the Football Association learns lessons from the "sorry saga" of harassment and bullying accusations.
During a discussion on the Me Too campaign, the model revealed she had been attacked as a teenager by an industry professional.