At least 18 other people were treated for injuries, authorities said.
Fourcase says the building is still very unstable, as well as the crane.
It was not immediately clear what caused the collapse.
As reported by nola.com, an eyewitness said: "It was a deep, rumbling sound, like an airplane maybe".
He asked that people stay away from the area and refrain from using drones for either personal or media purposes to view the damage.
WWL-TV aired a viewer's dramatic video of the collapse, showing upper floors falling on top of each other before one side of the building toppled to the ground. "This remains a very fluid and very unsafe situation, and every few minutes something is falling off of this building".
Johnson & Johnson must pay $8bn over drug side effect - jury
The drugmaker also faulted a judge's refusal to allow it to present mitigating evidence about Janssen's handling of the drug. The case, brought by Nicholas Murray, is one of 13,400 Risperdal-related lawsuits, according to J&J's latest SEC filings.
A number of building staff were working on the construction site, with the numbers still being accounted for.
NEW ORLEANS (AP) - A large portion of a hotel under construction in New Orleans has suddenly collapsed.
Surrounding buildings, including condominiums, were being evacuated.
The top six or eight floors of the building collapsed at about 9:12 a.m., according to McConnell. The rubble slid off the side of the building in insane video captured by onlookers in the street.
The development calls for 350 hotel rooms and condominiums.