An 86-year-old woman died in Gentilly, one of the areas hit hardest by Hurricane Katrina 18 months ago, and six other people were taken to hospitals, said James Ross, a spokesman for Mayor Ray Nagin. Ten structures were destroyed, he said; he did not know what or where they were.
CBS station WWL-TV reported that nine people were injured across the Mississippi River in Westwego, six of them in the Bon Soir Hotel, which lost its roof.
WWL-TV reporter Jonathan Betz said the hotel looks as if a "bomb went off" and that it is completely gutted.
The storm also tossed around FEMA trailers that had replaced homes destroyed by Hurricane Katrina and damaged dozens of homes and businesses, Westwego Mayor Robert Billiot said.
Public, private and parochial schools in Westwego closed. Xavier University in New Orleans shut down for the day because it had no power, spokesman Warren Bell said.
Several homes collapsed in other areas, officials said, and at least three people were taken to hospitals.
In New Orleans, the storm knocked down power lines and tree limbs and damaged roofs. About 20,000 people were without power in New Orleans, Westwego, and Metairie, a spokesman for Entergy Corp. said.
"There is just so much destruction," Billiot said.
Kevin Gillespie's trailer in Westwego was pulled five feet and shoved next to his steps so he couldn't open the door. The Federal Emergency Management Agency trailer behind his was pulled from its moorings and flipped into his back yard, Gillespie said.
"My next-door neighbors, they had just moved back into their house from (Hurricane) Katrina. Now it's totaled out again," he said.
He didn't know how badly his own belongings were damaged; a crew had only just cut off the gas. But the storm removed every vehicle he owned: "My car, pickup, motorbike and trailer all went away."
Still, he said, as dawn arrived, "The more damage I see there, the more fortunate we are."
At one point, emergency workers in New Orleans' uptown neighborhood scrambled to clear a downed magnolia tree so an ambulance could get by.
John Carolan, 50, who lives in the neighborhood, said he was awakened by the storm and got up in time to get into a closet with his wife.
"Ten seconds and it was over," he said.
He said the storm blew the furniture from his porch into the street.
Radar data provides "pretty convincing evidence there was a tornado," said meteorologist Robert Ricks in the National Weather Service office in Slidell. He said the damage appeared to be from one storm cell that was behind a squall line moving east, he said.
"It should be an improving trend the rest of the day," Ricks said.