In 1963 , the unarmed New Zealand Police lost four police officers killed by lone gunmen in two separate firearms incidents at Waitakere , Auckland in January 1963 and at Lower Hutt , Wellington in February 1963 . The detective who investigated the Waitakere killings recommended the creation of a unit to deal with armed offenders spending time with the New South Wales Police Emergency Squad . The AOS was formally started in August 1964 trained by the New Zealand Special Air Service ( NZSAS ) with the philosophy of " cordon , contain and appeal " . One of the highest-profile AOS interventions is their action during the Aramoana massacre on 13 – 14 November 1990 , which involved at least 150 police officers . Officers from the Special Tactics Group were also present at the crisis . Sergeant Stewart Guthrie , an NCO in the AOS , was killed in the massacre , although he arrived alone with only a revolver , ahead of the fully equipped team from Dunedin
Aramoana massacre
Aramoana massacre
Armed Offenders Squad