Story highlights Crimestoppers raises reward to $5,000 after dearth of tips in investigation

300 to 500 people had gathered at park for an impromptu music video filming

Officers were already in route to break up the gathering, when a firefight broke out

(CNN) A shooting in a New Orleans park left 17 people injured, and police say they know there are "hundreds of witnesses" who have yet to come forward with what they know.

Several hundred people -- estimates range between 300 and 500 -- had gathered at Bunny Friend Playground for an impromptu music video filming late Sunday when two groups began firing on each other, the New Orleans Police Department said in a statement.

"Witnesses told police that both groups left the park on foot immediately after the shooting," police said. Officers were already in route to break up the gathering, when the shooting broke out. ... They were about a block away when they heard gunshots."

Ten women and seven men -- 11 of them younger than 21 -- were injured and received treatment at area hospitals, Mayor Mitch Landrieu said in a news conference. Eight of them were transported to the University Medical Center trauma center.

Landrieu said he and Police Superintendent Michael Harrison visited victims in the hospital and were particularly impressed with a 10-year-old who told them he wanted to join the Army when he grew up.

Read More