Two men in the Canterbury town of Kaiapoi have been hospitalised with gunshot wounds early this morning.
Police said both were shot in the arm; the first man sought assistance about 3.30am and is in a serious condition.
The second man was dropped off at the hospital a short time later, but was not seriously injured.
Two people who were with the second man are now in custody.
Police said those involved in the incident were believed to know each other, and there was no risk to the wider community.
A police arming order has put in place across Canterbury following the shooting.