Staff at a convenience store in West Sussex were threatened at gunpoint by a lone robber.
The man went into the shop in Leylands Road, Burgess Hill, at about 1725 GMT on Tuesday and threatened post office staff at their counter.
Sussex Police searched the area but no trace was found of the man. No vehicle was seen.
The man was described as being in his 30s, between 5ft 7in (1.7m) and 5ft 9in (1.75m) tall and of stocky build.
He was wearing a dark coloured beanie hat, a beige stocking over his face, a blue hip length jacket, blue jeans and light coloured trainers.
Police said the robber pushed one member of staff to the ground, took the cash and ran up Leylands Road under the railway bridge and into fields in the direction of Blackthorns and Maple Close.
'Staff were shaken'
Det Insp Russ Sheppard said: "This is actually best known as the Worlds End area of Burgess Hill and was busy with traffic and pedestrians at the time of the incident.
"We are certain that people will have seen this man."
According to police, no shots were fired and staff were shaken but unhurt.
Several customers were in the store at the time but they were not "directly threatened".