Police are investigating seven sex attacks around a leisure complex in Manukau over the last two months.
The assaults took place in and around the Manukau Sports Bowl and the Gardens/Totara Park area.
One of the victims was aged 13.
"We are concerned about these types of incidents due to the nature and frequency of offending in these areas," said Detective Senior Sergeant Darrell Harpur.
"The latest occurrence was in broad daylight at a public playground. We urge people in the area to be vigilant and accompany their children to local playgrounds."