"They took cigarettes from the cupboard, and one said: 'Open the till or I'll shoot you'."
A car pulled up outside the dairy which scared the robbers off - "luckily", Patel added.
"I'm very lucky. If the customers hadn't have come they could have taken a lot more."
Customers outside managed to call police and record the thieves' number plate.
Husband Dipak was upstairs having a nap when his wife was held at gunpoint. He was relieved Usha was safe and had escaped the ordeal unharmed.
Although shaken after the robbery, Patel wanted to assure people she was alright.
She estimated the stolen tobacco products were worth around $800-$1000.
The couple's 13-year-old daughter, Richa, said she saw the two men from the living room window walking up the alleyway next to the shop before the attack.
She assumed they were "just normal people", as they hadn't covered their faces yet.
Moments later she heard yelling from the shop and ran to tell her father.
The Patels have owned the Hamilton dairy for 14 years, and were last hit with an attack in 2012, although nothing was stolen.
Police confirmed they received a call at 3.07pm yesterday reporting the incident.
A spokeswoman said one robber presented a pistol, but no one was injured.
"The pair have got into a waiting vehicle, and a quick-thinking member of the public has spotted this and supplied police with the registration."
Police staff conducted a check of an address linked to the vehicle, and located it.
Armed cordons were put in place and the vehicle was stopped as it left the address.
The 21 year old male driver was arrested.
The Armed Offenders Squad remained and cleared the address. CIB searched the property and located clothing and an imitation pistol.
"The driver has been charged with aggravated robbery and will appear in Hamilton District Court tomorrow."
Police are continuing to make inquiries.
