A man sustained a broken jaw and fractured skull after allegedly being assaulted on George Street in Hull on 2 December 2017.
The victim was taken to hospital for treatment after he was knocked unconscious during the altercation.
Police now want to trace four men and a woman in connection with this incident which occurred around 5.30am. The suspects may be from out of the region and possibly from the south of England.
CCTV images taken on the night of the suspects are not high definition (click below to view), but police are asking for anyone who may know the suspects or may have any information to please call 101 quoting log 112 of 2/12/17.