Gunmen opened fire on dozens of people marching in a Mother's Day neighborhood parade in New Orleans on Sunday, wounding at least 18, including two children, police said.

Police said many of the victims were grazed, and most of the wounds were not life-threatening.

FBI spokeswoman Mary Beth Romig said federal investigators have no indication that the shooting was an act of terrorism.

“It's strictly an act of street violence in New Orleans,” she said. The southern city has one of the highest violent crime rates in the U.S.

A news release said the wounded included two 10-year-olds. It also said two people were in surgery.

Police saw three suspects running from the scene. No arrests had been made as of late afternoon.

As many as 400 people joined what is known as a second-line parade, a loose procession in which people dance down the street, often following a brass band. They can be impromptu or planned.

Officers were interspersed with the marchers, which is routine for such events.

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 level before Hurricane Katrina devastated New Orleans in 2005.

Police vowed to make swift arrests.

“We'll get them. We have good resources in this neighborhood,” Serpas said. (AP)