Police are working with the victim, who is in a stable condition in hospital, to piece together exactly what happened but believe this is an isolated incident.
The unlawful use of firearms is of concern to police and inquiries into the matter are continuing.
Christchurch Police ask anyone who may have information on the incident to speak to Detective Senior Sergeant Leairne Dow on 03 363 7400. Alternatively, reports may be made anonymously to Crimestoppers on 0800 555 111.