Raiders threatened workers at an off-licence with a knife and escaped with £200.
A woman was serving at Thresher in Seaside, Eastbourne, just after 9pm on Saturday when two men burst in.
One of them held up a weapon, thought to be a Stanley knife, and demanded money from the till.
Police are appealing for witnesses to the raid, which left the woman badly shaken.
Both men were aged 19 to 20 and wore light-coloured checked scarves over their faces.
Both had beige baseball caps and one wore a dark denim jacket.
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