Young kids questioned over Qld zoo deaths

A seven-year-old is one of three children to be questioned over the callous killing of animals at a far north Queensland zoo.

Two lizards and a freshwater turtle were allegedly killed with rocks before their bodies were thrown into the Kuranda Koala Gardens crocodile enclosure earlier in the week.

Police say the children - aged seven, nine and 11 - were questioned before investigations were closed.

One has been cautioned and two have been counselled, they say.

Zookeepers told AAP they knew something was wrong after the attack when the park's kangaroos appeared spooked early on Monday morning.

A swift investigation found the dead eastern water dragons in a garden and the turtle floating in water.

Staff say they plan to install security cameras and increase perimeter patrols.

They believe the park was entered by cutting a hole in a fence.