Police say they responded to the incident in the Barrington St area near Lincoln Rd about 1pm, which related to "a family harm matter where a person was reported to have a firearm".
Armed police surrounded a house and a loudspeaker was set up outside the property.
"Police are making enquiries to locate a man following an incident in Addington, Christchurch, this afternoon," a spokesperson said.
"Initial calls were received relating to a family harm matter, where a person was reported to have a firearm.
"Cordons were put in place at an address.
"Two people from that address are assisting police with our enquiries to locate the person of interest who is no longer believed to be in the area.
"Another person involved in the initial incident has been transported to hospital with moderate injuries.
"The lockdown at a nearby school has been lifted and parents are able to collect their children as usual.
"Police acknowledge that this may have been unsettling for the young people whose school went into lockdown and appreciate their support.
"Enquiries remain ongoing to determine what exactly has occurred."
A St John ambulance was called to the scene. There was also a large police presence at the Z petrol station.
Addington Te Kura Taumatua school was also briefly placed in lockdown but that has now been lifted.
"Please do not come to school for School Cross Country. We are in a police-enforced lockdown. Your children are safe in their rooms. We will update as soon as we know more information. Please avoid calling school and tying up phone lines," the school said.
"I've just come through the Lincoln Rd Barrington St intersection and there's something serious happening there. Police cars blocking access from the motorway off ramp, and police with guns walking round."
