Another man - Jarrad Singer - was also shot.
Singer and Mokonuiarangi Chong have been charged jointly in relation to the violent fracas.
Tove Paranihi also faced the same charge - unlawfully possessing a firearm - but the case against her has since been withdrawn.
After the shooting a temporary general arming order was made - meaning all police on duty were carrying firearms.
A second order was made last night.
"General arming has been put in place in Canterbury District today following increased gang tensions which police are actively investigating this morning," said a police spokesperson.
"The order will be continually reviewed in line with our policy.
"The community should be reassured that police are taking action to mitigate any concerns."
Police could not say what specifically prompted the order.
The Kaiapoi shooting was the second major gang-related violent incident in early January.
On New Year's Day Kane Wayman was dropped off at Christchurch Hospital with critical injuries.
The Head Hunters associate died soon after.
He had been attending a party at a Mongols gang house on New Year's Eve.
Police raided that address hours after Wayman died.
Four people have been charged with his murder - three men and a woman - and are in custody awaiting their next court appearance.
All four have been granted name suppression as the investigation into Wayman's death continues.
