Court documents also revealed $293 was stolen from the supermarket and Lotto shop till.
The money and firearm were recovered by police when the teens were stopped in the vehicle heading towards Maungaturoto.
All three appeared in the Youth Court at Whangārei today jointly charged with aggravated robbery, unlawfully taking a motor vehicle, unlawful possession of a firearm and two charges of theft of petrol.
The petrol drive offs were at Z Taipa and Caltex Wellsford on the same day as the aggravated robbery.
They will reappear on Friday.Foodstuffs, which owns the Four Square brand, didn't say much except that no one was hurt during the aggravated robbery.
"Our team kept their cool and followed a process which kept them safe. Our key priority now is ensuring their wellbeing and giving them all the support they need," spokeswoman Sue Hamilton said.
The manager of Kaiwaka Motorcycles, Matt Dowson, was informed of the aggravated robbery by a customer about 30 minutes later and said it was good police had arrested those allegedly responsible.
His business is just across the road from Jaques Four Square.
"They were dumb enough to get flat tyres, went up the road to have it fixed and hung around town to be arrested. Good on police for doing their job," he said.
Whangārei police Detective Sergeant John Clayton thanked members of the public who recognised the trio's suspicious behaviour and reported it to police.
"We received several calls that directly led to locating the alleged offenders in this incident and we are grateful for the quick thinking and actions of those people."
He reminded the public to report any suspicious behaviour to police immediately.
"Often timely information can lead to the apprehension of offenders, who will ultimately be held to account for their actions. It's about creating safer communities together," Clayton said.