Police have been trying to figure out what sparked a gun battle in a crowded New Orleans park that left 16 people wounded and the mayor is calling on witnesses to come forward. Hundreds of people were gathered at a playground when two groups in the crowd opened fire on each other Sunday evening, AP quoted police as saying. Police were on their way to break up a big crowd at Bunny Friend Playground when gunfire erupted at the park in the city's 9th Ward, the police said in a statement. New Orleans Mayor Mitch Landrieu, speaking in a news conference aired on WWL-TV, called on people who were in the park to come forward with information. The police have also asked people who might have any video of the shooting to bring it to police. Police said 10 people were taken to the hospital in ambulances while another six were taken in private vehicles. Photos of the scene showed emergency workers wheeling some of the wounded to ambulances on gurneys while other people who appeared to be in pain lay on the ground.