A gang of boys aged as young as ten allegedly sexually assaulted a jogger and a 16-year-old girl in a south London park near Brixton.
The first incident happened on 11 August in Brockwell Park when two boys on bicycles, who were said to be aged between 10 and 12, approached a jogger and grabbed her buttocks.
The woman shouted at the boys who fled the scene after shouting abuse of a violent and sexual nature at her.
Five days, later a 16-year-old girl sitting with a friend in the same park was approached from behind by three boys, two aged between 10 and 12 and another aged between 11 and 13.
One of the boys grabbed the victim's breasts before she escaped his hold and stood up.
The boy then grabbed the victim again pulling her close to his body but she broke free and ran off. The boy then shouted abuse of a violent and sexual nature at the victim and exposed himself.
The first boy is described as a dark-skinned Asian male of slim build, with short straight black hair, big brown eyes and with a London accent. He is about 5ft 3ins tall, aged 10 to 12 and was wearing a grey zip-up hooded top and riding a dark bicycle.
The second is described as a black male of a slim build, with short black hair. He is about 5ft 3ins tall, aged 10 to 12 and has a London accent.
The third is described as a black male of a stocky build, with braided hair and a London accent. He is aged 11 to 13 and was riding a bicycle.
Trainee detective constable Jen Barley, the officer in the case, said: "This is very unusual and aggressive behaviour by males of such a young age.
"I know of two members of the public that stopped and offered help to the victims. Please would anyone that stopped or saw what happened get in contact with us."
Any witnesses or anyone with any information is asked to contact TDC Barley on 020 8649 2192 or call Crimestoppers anonymously on 0800 555 111.