Police in Christchurch say they are investigating a serious assault in the suburb of Shirley.
They say a 19-year-old man is in a serious but stable condition in intensive care at Christchurch Hospital.
The man was attacked at 11.30pm on Saturday, outside Shirley Primary School on Shirley Road.
He had been involved in an altercation with two youths, who along with two other young people, were spotted leaving the scene towards Emmett Street and Marshlands Road.
Police closed off Shirley Road at the intersection with Emmett Street, but it is now reopen.
Police say while some witnesses have come forward, they still don't know how the attack occurred.