Staff at the Post Office in Elton were left shaken after a robbery yesterday evening (December 3).
A man entered the Post Office on Ince Lane at 6.35pm and demanded cash.
He threatened workers before stealing a quantity of cash and fleeing the scene in a white van.
He implied that he had a weapon with him but no weapon was seen during the incident.
He is described as tall and of thin build. He had his face partially covered and was wearing a fluorescent jacket.
An investigation has been launched and enquiries are ongoing.
As part of those enquiries a white van was found abandoned nearby in Laurel Farm Close.
Police are currently trying to establish if this is the same van involved in the incident.
Det Insp Simon Lonsdale said: "We are taking this incident extremely seriously and are appealing to anyone who was in the area at the time and has witnessed what happened or has seen anyone acting suspiciously in the area to get in touch.
"The white van used in the incident was seen in the Laurel Farm Close area shortly before the robbery along with a dark coloured BMW and we believe that this car is also involved.
"I would urge anyone who has any information regarding the identity of the offender or the two vehicles involved to get in touch."
Anyone with any information is urged to call Cheshire police on 101 quoting incident number 774 of December 3 or Crimestoppers, anonymously, on 0800 555 111.