A robber jumped over a shop counter and stole £600 while his accomplice stood guard and threatened customers.
The two robbers raided the Co-op in Lowstock Place, Didcot, on Thursday at about 5.30pm.
One man jumped over the counter and demanded a member of staff opened the tills.
He grabbed £600 in cash and put it in a Co-op carrier bag.
A second man stood guard at the front of the shop, warning customers not to use their mobile phones.
As the robber was leaving, he spotted someone on their phone and grabbed a bottle of whisky and fled.
He is described as about 25 and between 5ft 10in and 6ft tall, with short dark hair. He was wearing a thigh length black Stone Island jacket with eight buttons down the front.
He was also wearing a black hat under a hood and white trainers. The second man is about 25 and heavily built.
He was wearing a bright red fleece-type jacket, a collar pulled up over the lower part of his face, dark tracksuit bottoms with two vertical white stripes down each leg and a dark beanie-style hat.
Dc Ian Leese said: "There were three members of staff in the shop at the time and two customers. The people were left shocked, but luckily no-one was injured."
Call police on 08458 505505 or Crimestoppers anonymously on 0800 555 111.
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