A VAN windscreen and flat window were smashed by ballbearings on Hylton Road, Sunderland.
Officers believe the offenders were using a catapult-type instrument to fire the ballbearings in the area at around 3.20pm, on Saturday, March 1.
Police are investigating the incident and are keen to speak to any witnesses or anyone with information.
Inspector Sam Rennison, from Sunderland Area Command, said: "Although only damage was caused during this incident, those responsible need to be aware that their actions could have been far more serious had one of the ballbearings hit someone.
"And while those involved may think this was just a prank, it is no joke. This act was criminal, they are breaking the law and they will be treated like criminals.
"We believe whoever was firing the ballbearings weren't too far away from Hylton Road so I'd urge anyone who thinks they may have seen those involved to come forward."
People can contact police on 101, extension 69191, quoting log number 939, 01/03/14, or the independent charity Crimestoppers on 0800 555 111.