Police hope members of the public may be able to help identify an offender whose attack on a young man last weekend left the victim with serious head injuries.
Detective Sergeant Mark Reid describes the incident as a "cowardly attack" on a 22-year old man.
He says police were called to an incident in Cashel St, Linwood, at about 2am on Sunday, November 25.
"Two men and a woman had got out of a taxi at the Cashel St address when they were approached by a group of four men and two women.
"There was an exchange between the two groups, and one of the four men from the larger group followed the group from the taxi up the driveway of the house.
"Two men have then been subject to a vicious and unprovoked attack by the man who had followed them. The offender punched one man twice in the face, knocking him to the ground.
"The second man stepped in to protect the first victim and was punched two or three times in the face. He fell backwards while unconscious, with the back of his head striking concrete.
"As a result he has suffered a fractured skull and brain bleed and was admitted into intensive care at Christchurch Hospital."
Detective Sergeant Reid says it is believed the offender then left the scene on foot with his associates.
"This was a cowardly attack that has left a young man with serious injuries.
"We really need the public's help to identify this offender, so that he can be held to account for his actions."
The offender is described as Maori, aged in his early 20s, of medium to stocky build, and approximately 1.7m (5ft 7in). He was wearing a black hoodie and black cap.
Anyone with information that may help to identify the offender, or who saw the incident, is asked to contact Detective Sergeant Reid on 363 7400.
Alternatively, to provide information anonymously contact Crimestoppers on 0800 555 111.