It is reported that the incident, which occurred on January 7, happened just after midnight as a 37-year-old man was chased from Park Road onto California Gardens - it is then alleged that the man was assaulted with metal bars.
The victim suffered serious injuries from the assault - which officers believe was a targeted attack - and required hospital treatment.
Investigating officer PC Laura Clarke said: “Since January officers have carried out extensive work to ensure that those involved in this incident are located and brought to the courts.
“If you know who they are or have any information about the incident that can help with our enquiries please call 101 quoting incident number 9 of January 7.
“Alternatively, you can stay completely anonymous by contacting the independent charity Crimestoppers via their website crimestoppers-uk.org or by calling their UK centre on 0800 555 111.”