A teenage boy was taken to hospital with head injuries after being assaulted in a park on the banks of Loch Lomond.
The 16-year-old was attacked next to the pier in Balloch Country Park at around 5.40pm on Tuesday.
He was taken to the Royal Alexandra Hospital in Paisley and treated for serious arm and head injuries.
Police are appealing for anyone who witnessed the assault to come forward.
Detective constable David Jamieson, of Dumbarton Police Office, said: “There were several groups of people around at the time of the incident and we would like to speak to anyone who saw what happened.
“If anyone has information, including mobile footage, that might help with our inquiries then please get in touch.”
Anyone with information can contact police by phoning 101.