A man was struck and killed by a Mardi Gras float during a Saturday night street parade in New Orleans, becoming the second person in days killed along a parade route during this year’s Carnival season, authorities said.

The man was fatally injured just before 7pm as the popular Krewe of Endymion float was rolling, New Orleans police said. He was pronounced dead at the scene.

Remaining floats that followed, along with marching groups, were diverted from the accident scene on Canal Street, a wide route popular with parade viewers in the Mississippi River port city.

The float, with its gaudy lights still twinkling, was cordoned off by police on horseback and on foot.

The fatality came as New Orleans was still mourning the death of a 58-year-old woman who – witnesses said – was run over by a parade float on Wednesday night.

A police officer at the scene in New Orleans. Credit: Max Becherer/The Advocate via AP

Mayor LaToya Cantrell said that the south Louisiana city was grieving.

“To be confronted with such tragedy a second time at the height of our Carnival celebrations seems an unimaginable burden to bear.

"The city and the people of New Orleans will come together, we will grieve together, and we will persevere together,” Ms Cantrell said in a statement.

“Our hearts break for those lost and for their loved ones, and our prayers and deepest sympathies are with them.”

Wednesday’s fatality had occurred during the parade of the Mystic Krewe of Nyx, an all-female carnival group.

Witnesses said the woman, New Orleans native Geraldine Carmouche, had apparently tried to cross between two parts of a tandem float and tripped over a hitch connecting the sections.

Tandem floats are multiple floats connected together and pulled by one tractor.

It was not immediately clear if a tandem float was involved in Saturday night’s fatality, but city agency NOLA Ready said that tandem floats would not be allowed for the few days remaining in the 2020 festival season.

The carnival season is nearing its traditional all-out Fat Tuesday celebration, the raucous climax of a week or more of parades, merrymaking and partying.

The Krewe of Bacchus will split its tandem floats for its Bacchus Sunday evening parade, the group said in a statement.

A statement from the Krewe of Orpheus said it would follow the city’s safety recommendations for its parade on Monday.

The deaths also come just a year after a car sped into a bicycle lane near a parade route, hitting nine people and killing two cyclists not far from where the Krewe of Endymion formation had just passed.

A man identified as the driver was subsequently charged with two counts of vehicular homicide.

Before this year, the most recent carnival float-related fatality in Louisiana happened in 2009, when a 23-year-old rider fell from a float and in front of its wheels in Carencro, about 120 miles west of New Orleans.

In 2008, a rider getting off a three-part float after the Krewe of Endymion parade in New Orleans was killed when the float lurched forward and the third section ran over him, police said.