Police Superintendent Ronal Serpas told reporters that a 10-year-old girl was grazed in the shooting around 2 p.m. She was in good condition. He said three or four people were in surgery, but he didn't have their conditions.
Officers were interspersed with the marchers, which is routine for such events. As many as 400 people joined in the procession that stretched for about 3 blocks, though only half that many were in the immediate vicinity of the shooting, Serpas said.
Police saw three suspects running from the scene in the city's 7th Ward neighborhood. No arrests had been made as of late afternoon.
Second-line parades are loose processions in which people dance down the street, often following behind a brass band. They can be impromptu or planned and are sometimes described as moving block parties.
A social club called The Original Big 7 organized Sunday's event. The group was founded in 1996 at the Saint Bernard housing projects, according to its MySpace page.
The neighborhood where the shooting happened was a mix of low-income and middle-class row houses, some boarded up. As of last year, the neighborhood's population was about 60 percent of its pre-Hurricane Katrina level.
Police vowed to make swift arrests.
"We'll get them. We have good resources in this neighborhood," Serpas said.