Four people were wounded on New Orleans' famed Bourbon Street as a costumed crowd partied amid the countdown to Mardi Gras.
The footage taken by a bystander and released by police showed two men leaving the argument and returning with a third before the gunfire erupted.
Four shots rang out rapidly, followed by screams as some in the crowd staggered into one another and a nearby wall.
Authorities said in an email on Sunday that an argument involving one of the victims led to the shooting.
Parts of the video were altered by police to show the three men they are looking for.
No arrests were immediately reported, and police said they were seeking the three men who fled.
The most seriously wounded of the four victims was listed in guarded condition on Sunday.
The other three were listed as stable.
The shooting happened at the height of Mardi Gras, New Orleans ' most famous event. Police have not identified the victims other than to say they were two men and two women.
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