Fire Chief Timothy McConnell told reporters at the scene the first call came in around 3:30 a.m.
McConnell said there were businesses on the first floor, but he was not sure about the upper floors. He said the fire started on the second floor of the four-story building.
One person was in the building, but escaped the flames without injury, McConnell said.
“Our main concern is to keep the flames from spreading to nearby buildings,” the chief said. He said the cause is under investigation.
He said it would be a while before the fire would be under control.
Live television images from the scene showed flames leaping from the roof. Several blocks of Canal Street, which borders the city’s French Quarter, have been closed.
Neighbors Michael Mallin and Kate Otto live in an apartment across the street from the burning building. Both were around the corner escaping eye sting smoke from the fire.
They were awakened by a fire alarm their building around 3:30 a.m.
“They told us it was safe to stay,” Otto said. “We decided we needed to get out.”