GUNMEN opened fire on dozens of people marching in a Mother's Day neighbourhood parade in New Orleans, wounding at least 19, including two children, police said.

Police said that many of the 19 victims were grazed and most of the wounds weren't life-threatening. A news release said the wounded included two 10-year-olds. It also said two people were in surgery. 10 adult men and 7 adult women were also among those hurt.

"Many of the victims were grazed (some by bullets that ricocheted)," a police statement said.

"At this point, there are no fatalities, and most of the wounds are not life-threatening."

The children -- a boy and a girl -- suffered graze wounds and were in good condition while a man and a woman were still in surgery.

One of the injured is a local reporter for Gambit Weekly Deborah Cotton who work colleagues say is now in a stable condition. A year ago Ms Cotton made a video on the culture of violence in New Orleans, watch it here.

Earlier, police said 12 people were shot and that three to four people were in hospital for surgery after shots were fired into the 400-strong crowd.

media_camera Mothers Day Parade Shooting: New Orleans police officers investigate the scene at the intersection of Frenchmen and N. Villere Streets in New Orleans after gunfire at a Mother's Day second-line parade. Police spokeswoman Remi Braden said in an email that many of the 17 victims were grazed and most of the wounds weren't life-threatening. No deaths were reported. (AP Photo/The Times-Picayune, Michael DeMocker)

The attack happened about 2pm United States Eastern Standard Time.

IN PICTURES: MOTHER'S DAY PARADE SHOOTING

New Orleans Police Department Superintendent Ronal Serpas said several hundred people were watching the traditional second-line parade when shots rang out at the intersection of North Villere St and Frenchmen St in the city's 7th Ward.

media_camera One of the wounded shot in 1400 block of Frenchmen Street in New Orleans. Picture: Lauren McGaughey NOLA.com

Police believe there were "maybe two different types of weapons," used in the incident, he added.

"Immediately after the shots were fired, our officers saw three people running away on Frenchmen toward Claiborne."

"It appears that these two or three people just for a reason unknown to us, started shooting at, toward or in the crowd," Serpas said. "It was over in just a couple seconds."

Officers were interspersed among the hundreds of marchers. That's routine for what is known as a second-line parade, in which people dance down the street, often following behind a brass band.

These loose processions can be impromptu or planned and are sometimes described as moving block parties.

Video | News | Weather | Sports Sun May 12 15:09:51 PDT 2013 Serpas: ’We will make them pay’ NOPD Chief Ronal Serpas on a shooting at a Mother’s Day Parade that sent at least 12 people to the hospital. view full article

Police have vowed to make swift arrests.

media_camera A wounded bystander at the Mother's Day parade in New Orleans. Picture:NOLA.cm/Twitter

"I think what frustrates all of us is the selfishness of some people, and I think what frustrates all of us is that the great culture of this city sometimes stumbles a bit because of the selfish behaviour of some people," Serpas said. "We can tell you without doubt that this police department will find these guys. We will find them, and we will bring them to custody and will make them pay for the crime they committed today."

Police have appealed to the public to come forward with any clues. A $US2500 cash reward has been offered to information leading to the arrest and indictment of those responsible.

"It's just a very tragic day for us," New Orleans Mayor Mitch Landrieu told reporters after visiting some of the wounded in hospital.

"We will find them," he said. "It really is important in this town for people to step forward now so that we can find people who do this and make sure that they don't hurt innocent victims anymore."

"It is important for us... to change the culture of death on the streets of New Orleans to a culture of life."

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.

The neighbourhood where the shooting happened was a mix of low-income and middle-class row houses, some boarded up. As of last year, the neighbourhood's population was about 60 per cent of its level before Hurricane Katrina devastated New Orleans in 2005. A week ago, three people were shot in the area and in February a 16-year-old girl was shot in both legs in the 7th ward.

Originally published as Mother's Day parade shooting