Detectives from Reactive and Organised Crime are investigating an altercation outside licensed premises in Portstewart around 1am on Wednesday.
Three people were taken to hospital and treated for minor injuries.
Two of the people involved are foreign nationals and police are investigating a hate crime element.
Eight people were arrested and have since been released on bail pending further enquiries – six of those arrested were off-duty police officers.
Chief Superintendent Garry Eaton said: “This investigation is still at the early stages and we are following a number of lines of enquiry including reviewing CCTV footage and identifying and speaking to witnesses.
“I would encourage anyone who was in the area of Church Pass in Portstewart during the early hours of Wednesday and witnessed the altercation to contact detectives in Coleraine.”
It’s understood that the ‘duty state’ of the six officers is currently under review.
Chief Superintendent Garry Eaton added: “Discipline Branch is also conducting an internal investigation and therefore it would not be appropriate for me to comment further however what I can say is that the Police Service of Northern Ireland expects its officers and staff to behave professionally, ethically and with the utmost integrity at all times.
“Any deviation from those standards is unacceptable and we are committed to ensuring that where officers and staff fail to maintain the high standards expected of them they are dealt with appropriately.”
Anyone who could assist with the investigation is asked to contact detectives in Coleraine on the non-emergency number 101.