The four-alarm blaze broke out at a Dollar K discount store on South Broadway in Yonkers around 4 p.m. Thursday, and it took firefighters six hours to get the flames under control.
About 200 people were evacuated, and dozens were being aided by the Red Cross.
Seven firefighters suffered minor injuries.
The dollar store was completely destroyed, and buildings on both sides were evacuated. A nearby school was turned into a shelter, and at least 25 people reportedly stayed there overnight.
Fire officials say 18 fire companies and 63 firefighters worked to put out the blaze.
The cause of the fire is under investigation.