Two men have been left with injuries to their heads, sustained during an attack during a race meeting at Goodwood.
At about 5.15pm on Friday 30 July, the victims, both aged 26, were assaulted by several other men in the racecourse side of the Gordon Enclosure .
It was the final afternoon of the July meeting.
Police arrested another 26-year-old man was arrested on suspicion of affray, causing actual bodily harm, and possession of cocaine.
After being interviewed he was released under investigation.
But a search was continuing on Sunday for the two other suspects.
PC Stephen Webb said:
"Our enquiries are continuing to identify and trace other men involved.
"If you saw the incidents and have any video footage, or if you can put names to any of the people allegedly responsible, please contact us either online or by calling 101, quoting Operation Newport."
The independent charity Crimestoppers also receives reports anonymously on 0800 555 111