Cindy Ding was confronted by the three young offenders while working at her milk bar in Macleod about 8am.
She said they demanded cash and cigarettes during the two-minute spree.
9News understands they fled the scene in a stolen Mercedes, which was stolen during an aggravated burglary in Vermont.
The ordeal left the business owner traumatised.
“I’m so scared every day to work in this shop… truly,” Ding said.
“I should be safe. I work so hard.”
9News understands the group also held up several service stations during their armed crime spree across the city.
The group attempted to rob a service station in Hampton, before they held another staff member at knife point at United in Bentleigh East.
A different group of offenders ransacked another milk bar in Bentleigh East.
The business owner Anna said she was “very scared” when the offenders stole money from the till along with some packets of chips at 2am.
Police are investigating the incidents.