A group of men and a child were spotted shooting swans and girls with a catapult.
Wiltshire Police is appealing for witnesses to the incident at a fishing lake in Swindon on Wednesday 25 August to come forward.
Officers investigating the incident say it happened at Plaum’s Pit lake, off Cheney Manor Road, at around 4pm.
They began shooting ball bearings at birds, including swans, on the water but later turned their attention to a group of girls in the area.
A spokesperson for the force said: “If you saw the men at the lake or have any information which could help our investigation, we want to hear from you.
“You can contact us online or call us on 101 quoting reference.
“You can also report anonymously by calling Crimestoppers on 0800 555111.”