The highlight for the kids - small and big kids alike - was getting up close and personal with members of the armed offenders squad. Mums queued for photos of kids holding a gun with a squad member.
It was standing room only at Monmouth Redoubt Reserve for the simulated demo in which Epic, the police dog, took down a "baddie" shooting at police, with the AOS moving in to take control.
Not that I am in favour of the glorification of guns.
But I am in favour of police being appropriately armed and trained.
Firearms have become "ridiculously easy" for offenders to get their hands on.
Read more: Epic day as police dog steals the show
Police are being confronted almost daily by gun-wielding criminals, according to the Police Association.
NZME reported this month that more than 500,000 firearms, worth $242 million, have been legally imported into New Zealand over the past decade.
These include high-powered hunting rifles, shotguns, pistols, semi-automatic weapons, and restricted air guns.
Police say they believe there are about 1.5 million guns in New Zealand.
There are about 230,000 licensed firearms owners.
It was thrilling seeing the armed offenders squad and handling guns at the open day.
But in the real world, guns are not play time.
I am glad the AOS is there to protect us and think more police should be trained and armed.
But gun licensing laws need revisiting.