Three children were detained in Rostov-on-Don on suspicion of brutally killing a kangaroo and three sea- gulls at a local zoo, a regional police spokeswoman said Thursday.

Two 12-year-old boys climbed over the fence Friday evening into the pen where eight kangaroos lived at the zoo, a spokeswoman with the Rostov regional branch of the Interior Ministry said by telephone.

The boys proceeded to beat a young kangaroo to death with sticks while a 10-year-old girl acted as a lookout, investigators said.

They also threw stones into a building where sea gulls are kept, killing three and severely injuring three others, police said. The children have admitted to the crimes, the regional Interior Ministry said in a statement on its web site.

The remaining seven kangaroos are in a state of "deep psychological stress," police cited a zoo employee as saying. The police spokeswoman could not say whether the attack had taken place during the zoo's working hours.

Rostov Police Two children, top, being interviewed for killing a kangaroo at a regional zoo.

The children were frequent visitors to the zoo and were seen by employees of a cafe on the premises climbing out of the kangaroo's pen Friday. They were detained Wednesday after returning to the zoo and subsequently confessed to police, authorities said.

The girl is the sister of one of the boys, while the other boy has been expelled from school and will be sent to a school for children with learning disabilities, police said.

The children have been returned to their parents, who could be fined up to 80,000 rubles ($3,000) if a court finds the children guilty of animal cruelty, the police spokeswoman said. No date has been set for a court hearing.

It was not the first time that kangaroos have been terrorized at the Rostov-on-Don zoo with tragic results. Ten years ago attack dogs were sicked on the kangaroos, killing all eight of them living there at the time, the regional Interior Ministry said.