NEW ORLEANS (CNN) -- One minute, a man stands at the outskirts of a packed parade route. The next, he charges toward them.
The scene is part of dramatic surveillance camera images of a shooting that turned a festive New Orleans Mother's Day parade into chaos and renewed concerns about crime in the city.
The images, released by police Monday, show the panicked crowd scrambling for cover. The man runs the other way, leaving scattered bicycles and bodies on the ground behind him.
It's the third holiday this year when guns have been fired into crowds, New Orleans Mayor Mitch Landrieu said. A Jan. 21 shooting near a Martin Luther King Day parade left five wounded. Four people were hurt in a February Mardi Gras attack, the New Orleans Times-Picayune reported.
Sunday's shooting, which injured 19 people, sparked worries that despite the number of witnesses, no one will come forward. After years of corruption, a deep-seated distrust of police lingers among some of the city's residents.
Authorities vowed to catch the shooters.
"We're going to be very, very aggressive," Landrieu said Sunday, calling for witnesses to report what they saw to authorities. "There were hundreds of people out there ... so somebody knows who did this."
Remi Braden, a police spokeswoman, described the shooting as "an extremely unusual occurrence."
"We're confident that we will make swift arrests," she said, adding that members of the community have provided tips to authorities.
Witnesses were hard to come by Monday across the neighborhood, dotted with houses that have barred or boarded-up windows, overgrown lawns and patchy roads in need of paving.
A ripped T-shirt filled with bullet holes hung from a nearby light post, and a pair of old sneakers dangled from a power line.
Abdul Aziz, 33, told CNN's iReport that he saw a gun's muzzle flash at Sunday's parade but couldn't see who the shooter was.
"I'm sad. I love this city," he said. "We're plagued by crime, and it's just not getting better, no matter what we do."
The shooting took place at one of the city's famed second-line parades about two miles from the heart of the French Quarter. The dancing and brass band processions happen nearly every Sunday, except during the hottest months of summer.
The Original Big 7 Social Aid and Pleasure Club, which organized Sunday's parade, decried what it called a senseless attack.
"Secondlining is about community and celebration, not trauma and violence," the group said in a statement, describing crime and violence as systemic problems in the city.
"We feel embarrassed that the world is now viewing our city and our community through a lens of violence," the statement said. "We support a thorough investigation of the shooting and pray the perpetrators will be brought to justice."
The violence took place as New Orleans undergoes an expensive and sweeping overhaul of its police department ordered last year by the U.S. Department of Justice.
And the shooting comes less than a month after federal prosecutors announced the high-profile indictment of five New Orleans gang members on gun and drug charges. The indictment was the first returned as a result of a new multiagency police unit dedicated to rooting out violent gangs in the city, but authorities vowed that it would not be the last.
Asked whether the parade shooting was gang-related, officials said they were still investigating.
"It's too preliminary to tell," Landrieu said, adding that he expected more information later.
"It's a culture of violence that has enveloped this city for a long period of time ... and it's one of the things that we as a community have got to stop," the mayor said.
The attack included shots that were fired from different guns, police said, and officers saw three possible gunmen running from the scene.
On Monday, at least three victims were in critical condition, said Louisiana State University Medical Center spokesman Marvin McGraw. One other victim was in stable condition at the hospital, he said. Seven others had been released. Conditions of other victims were unclear.
Federal investigators say they have no indication that the shooting 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.
CNN's Jason Morris reported from New Orleans. CNN's Catherine E. Shoichet reported from Atlanta. CNN's Dana Ford and Thom Patterson contributed to this report from Atlanta.
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