Staff at Spalding’s Carphone Warehouse were robbed of cash and mobile phones at knifepoint on Thursday.
The incident happened at around 6pm when two men, both described as Afro Caribbean, went in the Winfrey Retail Park store and took cash and a number of phones.
Members of staff were threatened with a knife but no-one was injured.
Police are urging anyone with information to call 101.
Officers would specifically like to speak to anyone who witnessed the incident or the vehicle involved, a white Audi 4×4 sports car, that may have been driven erratically from the scene.
Call 101 quoting incident reference number 324 of May 14, with information for the investigating officer DS 749 Dovaston.