It happened around 8:17 a.m. in Chelsea on West 29th Street between 7th and 8th avenues.
The New City Fire Department says a box truck pulling out of its space caused the collapse and dominoed to the adjoining shed.
One person was critically injured and two other people suffered serious injuries. All of the injured victims, a 21-year-old man, 20-year-old man and 30-year-old man, were taken to Bellevue Hospital and are expected to survive.
The 62-year-old driver of the box truck stayed at the scene. He tried to help the victims and is devastated by what happened.
There was a large emergency response with 12 FDNY units and 60 members responding to the scene.
Department of Building (DOB) officials said the sidewalk shed that collapsed is associated with 231 West 29th Street. They say the owners had an active permit to legally have a sidewalk shed in place.
The DOB issued an administrative violation to the property owners to fix their shed, but said they didn't do anything wrong.
Sidewalk sheds are on almost every street in the city and some linger for years. Council member Eric Bochner hopes the city passes legislation to limit how long they stay up.
"There's no reason why New York City should have nearly 400 miles of sidewalk covered by these sidewalk sheds, you don't see them in any other city to this degree," Bochner said. "So we at the council have a package of legislation that we're hoping to get passed in the near future."