A driver has been punched in the face while stopped at the exit of the Co-op Grande Marche in St Helier.
Police are appealing for witnesses to an altercation at lunchtime on Tuesday.
A man in his 40s driving a VW Transporter was letting people cross when a man approached the vehicle from behind and hit it with his hands before hitting the driver through the open window, damaging his teeth.
A 49 year old man has been arrested on suspicion of Grave and Criminal assault and released on police bail while enquiries are ongoing.
Officers want to speak to anyone who saw what happened, or who has CTV in the area or any dash-cam footage.
Witnesses are asked to contact police on 612612 or the independent charity Crimestoppers anonymously on 0800 555 111 or via their Anonymous Online Form at Crimestoppers- uk.org