New Orleans Mayor LaToya Cantrell confirmed a second death Saturday night, and said a third person remained missing, after a Hard Rock Hotel and Casino building under construction in the city's downtown area partially collapsed earlier in the day.

More than 20 other people were reported injured in the collapse.

"We can confirm we have lost two people, a third has not been found just yet so we don't know. We have not been able to identify the three individuals," Cantrell told local station WWL-TV.

The bodies were spotted by search teams inspecting the damage after the collapse, but the remains could not be recovered, the station reported. Cranes capable of lifting the collapsed portions of the hotel structure were being transported to New Orleans as part of the response effort, according to the station.

Gov. John Bel Edwards confirmed the first fatality earlier in the day.

New Orleans Fire Department Chief Timothy McConnell confirmed earlier that an urban search-and-rescue team was preparing to sweep the building for any possible bodies or trapped survivors.

"This remains a very fluid and dangerous situation and every few minutes something is falling," Edwards said, warning people to stay away from the area.

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McConnell said the department received a call about the fallen building around 9:14 a.m. Saturday. He said the top six floors of the building collapsed and that the rest of the construction was "very unstable."

EMS Director Dr. Emily Nichols also added that the number of individuals who transported themselves to the hospital was "somewhere in the double digits." She also said that all who had been hospitalized are in stable condition and several patients have been discharged.

"It's still a very dangerous situation," he said. "The crane is still in place but it is unsupported and very dangerous. We are in the process of evacuating the buildings in the perimeter."

McConnell said that the crane is approximately 270 feet tall and more, possibly larger equipment will be needed to stabilize it.

Mandatory evacuations have been ordered for the uptown side of Bienville Street, the downtown side of Canal Street and lakeside of Burgundy Street as well as additional road and traffic closures spanning further out of the area, officials announced.

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The building collapse was caught in a dramatic video.

The cause of the collapse wasn't immediately known.

"The frame of the building is considered stable but is unsupported, and therefore the situation is considered dangerous and residents are strongly encouraged to avoid the area until further notice," LaTonya Norton, a spokeswoman for New Orleans Mayor LaToya Cantrell. said.

The fire department ordered the evacuation of nearby buildings.

"It sounded like a -- I don't know how to describe it -- like a building coming down," said Matt Worges, according to Nola.com. He witnessed the collapse from a Tulane School of Public Health classroom in a nearby building.

"It looked like the concrete just slid from the top all the way down to the street," Worges said. "The concrete just started to slide down the side."

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The building was under construction at the corner of Rampart Street and Canal Street, a broad boulevard just outside the the city's famous French Quarter, lined with restaurants, hotels and retailers. Canal, which carries six lanes of traffic divided by a wide median where streetcars roll, separates the Quarter from the city's main business district.

The development calls for 350 hotel rooms and condominiums. Plans were unveiled last year. The hotel was scheduled to open in the spring.