A 20-year-old man from Crawley has died following a hit-and-run on Brighton seafront (A259).
The man, who has not yet been named, was suffering from serious head injuries when he and two others were hit by a BMW following a fight in the early hours of Sunday morning.
The incident happened in Marine Parade at approximately 05:20 GMT.
A murder inquiry has begun, Sussex Police said.
A man, 33, held on suspicion of attempted murder remains in custody. A 32-year-old man held on suspicion of causing grievous bodily harm has been released while inquiries continue.
The two other injured men, aged 18 and 22, are in a serious condition in hospital, police said.
Sussex Police confirmed the incident was not terror-related.