On the way out one of the offenders grabbed a bottle of water retailing for about $3. As the robbers ran off, one of the workers chased them down Broadway with a broom he'd been using to sweep up.
Mr Johnston said it was "perfectly legitimate" for people to defend themselves in the way staff at the dairy had, but police didn't recommend it.
"Our advice (is) it's only property, it's not worth risking an arm, or worse, to a meat cleaver."
CCTV footage showed just how close the weapon came to a shop worker's arm. If it had connected the result would have been a severe injury, he said.
Mr Johnston urged anyone who recognised the youths, or had seen them hanging around town earlier in the day, to call the Kaikohe station on (09) 405 2960 or Crimestoppers on 0800 555 111.
They had disguised themselves before entering the dairy but Mr Johnston was confident someone would know who they were.
During the robbery the youths were "hopping around so much" some of their bandannas fell off, exposing their faces to the security cameras.
"We're hoping someone will be able to identify them before they hurt themselves or someone else."
The superette is owned by Hemant Patel and his brother, who were working at the time along with Mr Patel's wife.
It was the first robbery in the two-and-a-half years they had owned the shop.
"It was scary, but we handled it," Mr Patel said.
He hoped the offenders would be found and taken to court.
"They tried to kill us," he said.
The robbery at Tui Superette comes less than a fortnight after an armed robbery at Kaikohe McDonalds. In that case, three men armed with an axe and a shotgun smashed their way into the fast food outlet about 11pm on August 23 and ordered staff to hand over money from the till and office. They are still on the run.
On August 27 five boys, the youngest aged just 14, held up Waipapa BP and made off with the cash drawer, cigarettes and chocolate. Four alleged offenders were arrested that night; the fifth was caught in Kaitaia yesterday. The three robberies are not believed to be connected.