DENVER -- They are not calling it a "turf war," but Denver city officials are admittedly concerned about a growing number of reported gang problems in City Park.

During the first couple of weeks of the summer-long Sunday night jazz series, attendees and organizers reported seeing dozens of suspected gang members dressed in all blue and others in all red.

The park is considered one of the Mile High City's treasures by Mayor John Hickenlooper.

"I used to run a lot of races here," said lifelong Denver resident Dino Marez. "(My family) love(s) it. They come to the planetarium and stuff like that. We enjoy the park."

But now, officials said a growing presence of rival gangs at the jazz series is concerning.

"You know, our goal is to make sure that every park is safe. And not only that, but to make sure that kids and families feel safe walking from their homes to the park," said Denver Mayor John Hickenlooper.

"And we can't let any park -- City Park, Washington Park, Sloan's Lake -- slip into that netherworld where gangs are fighting it out or sprouting their colors," Hickenlooper added.

Terrance Roberts was shot in the back during the Summer of Violence in 1993. He has since left the gang he belonged to at the time. Roberts now runs an after-school program dedicated to saving kids and giving them exposure to life outside the inner city.

"There's always been a presence of one particular gang (in City Park), but now we have other gangs saying, 'You know what? We want to go there, too.' And it's starting to get ugly," Roberts said.

"We need to blanket the park with people who live normal lives instead of people who are there for the wrong reasons," said Roberts.

"We're not going to blink. We will make sure that we will have a stronger police presence there, and we will continue to work to find more summer jobs, more rec. center activities, to kind of give these kids better choices," said Mayor Hickenlooper.