A staff member was allegedly assaulted from behind during the incident, which caused him to fall to the ground, before the group absconded from the scene.
The staff member did not require medical treatment.
Specialist police units attended the scene a short time later and arrested six teens nearby.
A 14-year-old Wyndham Vale boy, 14-year-old Albanvale boy and a 15-year-old Sunshine West boy have been charged with armed robbery and will face a children’s court on Monday.
A 14-year-old Sunshine North boy was charged with recklessly cause injury, a 14-year-old Hoppers Crossing boy was charged with theft and a 16-year-old boy was charged for theft on unrelated matters. All three were bailed to appear at a children’s court at a later date.