They demanded the female worker behind the counter to open the till, after which they allegedly stole more than $200.

The owner’s mother then noticed what was going on and locked the front door to the milk bar, trapping the thieves inside.

“She was very brave to stand there and when they come back to try and get through the door, she’s still standing there and she could be dead,” a witness said.

Failing to find another way to escape, the armed group tried to smash open the front door.

They then demanded the staff member give them a key and left through a side door.

No one was physically harmed during the incident.

Police are working to determine whether the incident is linked to any others, including a robbery at an Endeavour Hills milk bar on Sunday.

The group remains on the run. and police are urging the public to come forward if they have any information.