The incident happened just after 11:30 a.m. near the intersection of Broadway and Prince in SoHo.
Pictures from the scene show wooden planks all over the street, and FDNY firefighters at the scene.
FDNY officials said "we're absolutely lucky" there aren't more injured in this busy neighborhood. There is a subway stop right at the intersection, and the area was packed with people out enjoying their Sunday morning.
Investigators said strong wind is to blame for the collapse. A piece of plywood "acted like a sail" and blew the whole rig down.