Boys as young as 13 were chased by knife wielding teenagers in Newbury's Victoria Park on Saturday.
The group of seven 13-year-olds were chased through the park in broad daylight at 1.45pm on Saturday, October 24.
Two youths, aged around 16, followed and chased the boys and one was carrying a knife.
The offenders were described as white and between 5ft 4ins and 5ft 6ins tall.
One was slim and the other was of a large build. They were both wearing dark clothing with hoods up. One of them was wearing a balaclava over his face.
PC Angela Howell from Newbury police station said: “This kind of behaviour will not be tolerated. We are conducting a thorough investigation.
"If you have any information about the incident please contact me via the 24-hour Thames Valley Police enquiry centre on 101.
If you don’t want to speak directly to the police, you can contact the independent charity Crimestoppers anonymously on 0800 555 111 No personal details are taken, information is not traced or recorded and you will not go to court."