A damning police report on the 2016 Kawerau siege says different tactics could have prevented four officers being wounded.
The 22-hour operation took place in March 2016 and ended with 28-year-old Rhys Warren surrendering to a Māori liaison officer.
The report, released this week under the Official Information Act, reveals the outcome could have been different had there not been a lack of communication between the armed offenders squad and command centres.
Forty-six rounds were fired from police in the siege, making it the most shots fired in a single incident in New Zealand's recorded police history.
The decision not to use tear gas or police dogs, instead of raiding the house, was also criticised.
In March 2017 Warren was found guilty of six charges - two counts of attempted murder, three counts of using a firearm against law enforcement and a charge of wounding with intent to cause grievous bodily harm.
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