Two men armed with machetes threatened staff at a Coop store in Sale.
Police were called to reports of a robbery at the supermarket, on Northenden Road, in the town centre.
Two men, armed with the weapons, burst into the store and threatened staff.
Police have been unable to confirm at this stage if anything was taken.
Read more of today's top stories here
Nobody was injured during the incident, but the staff members have been left shaken.
Greater Manchester Police have launched an investigation following the incident which took place at 10.15pm on Sunday, October 6.
Anyone with information can contact GMP on 101, quoting incident number 2956 of 06/10/19.
Reports can also be made anonymously to the independent charity Crimestoppers on 0800 555 111.
