Details about victim weren't immediately available, the (New Orleans) Times-Picayune reported.
Elsewhere, Rex 2014, aka Jack Laborde, toasted the Queen of Carnival, Carroll Irene Gelderman, and noting the chilly, wet weather said, "All y'all gotta be crazy."
"But this is what we do," Laborde said.
Mardi Gras 2014 officially began after 6 p.m. Monday when Laborde, and King Zulu 2014, Garren Mims, met along the Mississippi Riverfront and Mayor Mitch Landrieu handed Rex the key to the city of New Orleans for a day.
As Rex, Laborde smiled at his subjects and he and his 27-float entourage moved along the 5.2 mile parade route in New Orleans.
The theme was "Gods of All Ages" and float riders tossed medallions representative of the deity the float depicted.
A Loyola University sign along St. Charles Avenue was vandalized, but witnesses said such vandalism happens so often that maintenance crew keep extra letters available. The missing letters -- L, O, Y and O -- will be replaced Wednesday.
Fat Tuesday is a celebration of gastronomical delights before the fasting and penitential Lenten season begins the following day, Ash Wednesday.