"The walls started moving, then the bang. Everything started coming down. Everyone started screaming," said Abigail Reckermann, 50, who went to the hospital with a swollen ankle.
Injuries to three of the injured were life-threatening, authorities said.
Ambulances and fire trucks converged on the scene, in downtown's East Village neighborhood.
Investigators did not know what caused the collapse, fire spokesman Daniel Calderon said.
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