"When he entered and their scary looks, we knew they were after money so we emptied two tills and gave them all the money we had and then they demanded cigarettes which we handed over to them as well."
The shop assistant said the three carried a black bag and a garbage bag used to put cigarettes in.
The ordeal lasted one minute and 15 seconds, according to CCTV footage which has been handed over to police.
All three ran towards First Ave through an alleyway beside the shop.
The shop owners employed a security officer after the first two robberies but they have not had one for more than two years.
They will now lock the shop after dark when customers are not inside.