Two masked robbers threatened shop workers with a knife before stealing from the tills on Monday in Ingoldmells.
A female assistant was putting trolleys outside the Tesco Express shop on Sea Lane when she was approached from behind.
The thieves took her back into the shop to steal cash before leaving in what is believed to be a silver Peugeot.
It’s not yet known how much money was stolen in the raid on Monday, May 6 at around 5am.
Both of the shop assistants were left very shocked, but they were not injured.
Lincolnshire Police are investigating the robbery and have urged anyone who was in the area at the time to come forward.
Anyone who saw the masked men, one described as about six feet tall and the other short and stocky to call 101, quoting incident 71 of May 6.