Sussex Police said the incident in Littlehampton was reported at around 6am on Sunday.

The victim, who was a local, was pronounced dead at the scene on Gladonian Road.

The teenager remains in police custody.

Police have appealed for anyone who was in the area on Sunday morning to come forward.

The senior investigating officer, Detective Superintendent Andy Wolstenholme, said: "We understand this is a shocking incident for a close-knit community in Littlehampton.

"My condolences are with the family and friends of the victim, and anyone affected by this death.

"We are working hard to establish the facts surrounding the tragic events of last night, and need the assistance of the public to do so, especially by calling in if you were in Gladonian Road between midnight and 6am, either on foot or in a vehicle.

"It would also support the investigation if any social media posts did not speculate about what happened. If you have information, please call in to the police and we will take that information from you."