Police are investigating an alleged gun-point robbery involving youths in Lancing.
A 16-year-old boy was with his friend at Monks Recreation Ground in Crabtree Lane at around 10pm on Wednesday 26 October when he was approached by three men.
One of them, reportedly in possession of a firearm, demanded property from the victim before taking it.
The boy was then assaulted by the group.
The three suspects ran off in the direction of Lancing railway station.
Following enquiries, a 16-year-old boy from Shoreham was arrested on suspicion of robbery. He has been released on conditional bail.
The two other suspects are yet to be identified and found.