The crime scene was about 1.5 miles from the heart of the French Quarter and near the Treme neighborhood, which has been the centerpiece for the HBO TV series "Treme."
Sunday's violence comes at a time when the city is struggling to pay for tens of millions of dollars required under federal consent decrees to reform the police department and the city jail. The mayor initially backed the police reform agreement and had sought a comprehensive civil rights investigation of the department when he took office in 2010. However, he is trying to put the brakes on the reform plans. In January, he said the city can't afford to spend millions required under the police reform agreement and the jail agreement reached separately between the Justice Department and Sheriff Marlin Gusman, who runs the city-funded jail.
The agreement to reform the police department came after a scathing Justice Department report in 2011 said the city's officers have often used deadly force without justification, made unconstitutional arrests and engaged in racial profiling. A series of criminal investigations focused on a string of police shootings in the aftermath of Hurricane Katrina in 2005.
Shootings at parades and neighborhood celebrations have become more common in recent years as the city has struggled with street crime, sometimes gang-related.
But police vowed to solve Sunday's shooting. Serpas said it wasn't clear if particular people in the second line were targeted, or if the shots were fired at random.
"We'll get them. We have good resources in this neighborhood," Serpas said.