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
Jim Carrey apologises after using a photo of an autistic boy to promote his claims vaccines contain harmful neurotoxins
Newly released files show a proposal to move the population of Hong Kong to Northern Ireland
Thatcher government feared banning Saddam Hussein from making chemical weapons after discovering UK firm supplied a factory with equipment