Police were called at 9.48pm to a report of an altercation in Tokyo Joe’s nightclub, in Guildhall Walk.
Four men suffered slash or stab wounds in the incident, however none of the injuries suffered are life-threatening.
Officers made two arrests after attending the club.
A 20-year-old man from Portsmouth has been arrested on suspicion of causing grievous bodiy harm with intent, possession of a controlled drug of Class A, and possessing an offensive weapon in a public place.
A 15-year-old girl was arrested on suspicion of common assault and using threatening, abusive or insulting words or behaviour to cause harassment, alarm or distress.
Both remain in custody at this time.
Detectives are conducting enquiries today and are keen to hear from anyone who can assist the investigation, in particular anyone with mobile phone footage of the incident.
If you can assist with enquiries, please call 101, quoting the reference 44220450835. Alternatively, you can call Crimestoppers anonymously on 0800 555 111.