(CNN) -- Federal investigators say they have no indication the shooting at a Mother's Day parade in New Orleans was an act of terrorism.
"It's strictly an act of street violence in New Orleans," New Orleans FBI spokeswoman Mary Beth Romig said Monday.
Such parades -- local traditions replete with dancing and brass bands -- are known as second-lining. They happen most every Sunday, except during the hottest months in summer
Shots were fired from different guns Sunday, and officers saw three suspects running from the scene, police said.
The shooting injured 19 people, including two children, police said. Ten men and seven women were among the victims.
The children were grazed. Other injuries ranged from minor to severe.
One of the assailants was described as an African-American male, approximately 18 to 22 years old, wearing a white T-shirt and blue jean shorts. No one was in custody.
"This is an extremely unusual occurrence, and we're confident that we will make swift arrests," said Remi Braden, a police spokeswoman.
Police Superintendent Ronal Serpas told CNN affiliate WVUE that it appears that "two or three people just, for a reason unknown to us, started shooting at, towards or in the crowd."
He asked anyone with information to call authorities.
New Orleans Mayor Mitch Landrieu echoed that request, challenging the community to get involved.
"It's important for us, as I have said, to change the culture of death on the streets of New Orleans to a culture of life, and it's going to take an all-hands-on-deck approach," he said.
"These kinds of incidents are not going to go unanswered. We're going to be very, very aggressive. There were hundreds of people out there today, so somebody knows who did this."
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