Police are now seeking witnesses to the alleged “grave and criminal assault”, which they believe happened around 19:25.
In an appeal for more information, the Force said: “Officers were called to the scene by the States of Jersey Ambulance Service.
“A group of youths were involved in an altercation inside the store, and a 16-year-old boy was found with a head injury.
“He was taken to hospital where he remained overnight, and has since been discharged.
“Five suspects have been arrested in connection with the assault, and subsequently released on police bail.”
Pictured: The 16-year-old had to remain in hospital overnight, but was discharged today.
Anyone who saw what happened or who has more details is urged to call 612612 or make an anonymous report using the Crimestoppers website.