Essex Police are continuing their appeal for witnesses over the raid at the One Stop in Elsenham on Tuesday (September 1).
Detectives are particularly keen to hear from anyone who saw a white van, similar in size to a Ford Transit, in the area.
Police were called to the One Stop convenience store in Robin Hood Road, shortly after 6.10am on Tuesday.
Two staff members, a 21-year-old man and 25-year-old woman, were threatened and tied up, before robbers stole a four figure sum of cash from the shop.
They left in a white Ford Transit-sized van with a sliding door on the left hand side. The registration plate of the van may have started with the letter S.
Anyone with information is asked to contact Braintree CID on 101. Alternatively, they can contact Crimestoppers anonymously on 0800 555111 or www.crimestoppers-uk.org.
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