The robbery involved four men and happened at a shop in Carr House Road, Shelf, yesterday (Thursday) at 4pm.
Two of the men entered the shop, one of them carrying what was thought to be a weapon, and threatened staff.
The two other men waited outside before all the suspects fled the scene.
Detectives have today (Friday) released CCTV images of two of the men they are trying to trace.
Detective Constable Anil Seepujak, of Calderdale CID, said: "Although nobody was injured, the victims will undoubtedly have been frightened and fearing for their personal safety.
"We are keen to trace these men and anyone who has any information as to their identity is asked to call police."
The suspects are described as being white and approximately 17-18 years of age.
One of the suspects was of medium build, 5ft 7ins tall, with light shaven hair and was possibly wearing a baseball cap and dark-coloured hooded top with matching bottoms.
The second was of similar height and build.
Suspects three and four are believed to have waited outside and were both described as being 6ft tall.
Suspect three had short hair and was of medium build, while suspect four was described as being of large build and was wearing a hooded top.
Anyone who recognises the men pictured or anyone with any information are asked to call Calderdale CID via 101, quoting reference 13170121562.