It happened at the Shell Garage, Sourton Cross in December.
Police say they'd like to speak the two men and the woman pictured because they are thought to have vital information about the incident.
A man entered the service station on the A386 at around 3.45am on Tuesday 10th December.
He became aggressive, tried to jump over the counter and repeatedly threatened to “knife” the sales assistant.
Anyone who witnessed the incident or knows any of those pictured is asked to contact 101 quoting, CR/110723/19.https://crowd.in/dnWiJQ
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