Police in Douglas are appealing to drivers who saw a group of men fighting near the old Noble's hospital in the middle of the day on Thursday to come forward.
An incident described as 'violent' spilled from the site onto Westmoreland Road at around 2pm on 16 May.
It's thought several motorists stopped because of the fracas and although some witnesses have come forward, police want to speak to anyone else who saw the incident and hasn't yet contacted them.
Four men were arrested.
If you have any information contact Lord Street police station on 631212 or Crimestoppers on 0800 555 111.