1 World Trade Center -- Window Washers Dangling 68 Floors Up

12:13 P.M. PST -- Federal investigators tell TMZ they want to know what caused the scaffolding to malfunction. We're told OSHA (Occupational Safety and Health Admin.) has launched "an inspection" into the incident.

11:23 A.M. PST -- Both window washers have been rescued. NY firefighters broke open a window and pulled the workers to safety. The FD just updated its Twitter feed, reporting "scaffolding emergency, under control."

Two window washers are stuck on a scaffolding outside the 68th floor of 1 World Trade Center in New York City ... and the FDNY is staging a rescue.

The workers were reportedly heading to the top of the building at around 12:42 PM ET when their scaffold's motors or cables broke.

The FDNY will reportedly break through the glass of the building in order to get to the workers. More than a dozen FDNY units have been dispatched to the scene.