Armed raiders struck twice on Boxing Day night.
And detectives believe the raids in Dewsbury and Batley may be linked.
No-one was hurt but the thugs were armed with a hammer and a knife.
The raids follow an attack in Huddersfield on Christmas Day.
In that incident, a shop worker wrestled a gun from an armed robber who struck at the Long Lane Convenience Store in Dalton at about 7pm on Christmas night. He fled with cash.
Police said the suspect entered the shop with their face covered and what looked like a hand-gun. It is not known if the criminal is a man or a woman.
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Det Insp Steph Wiseman, of Kirklees CID, said: “The suspect gained entry between 6.55pm and 7.10pm carrying a black handgun.
“They made demands for the money in the till, which they have got away with.
“During the robbery there was a struggle with a shop worker who managed to get the gun. We think it’s either a ballbearing gun or a pellet gun but we’re waiting to get the results.
“The suspect ran off down Longfield Avenue.”
No one was injured in the struggle.
The first raid on Boxing Day was at the News Gallery shop in Heckmondwike Road, Dewsbury, at 6.50pm.
A man was behind the counter and his wife was in the back of the shop when two men walked in. One, wearing all black, had a hammer and started attacking the cash register. It is not known what was stolen.
The robbers were chased from the shop and vanished.
Two hours later, two men went into Healey Mini Market in Batley where a lone worker was behind the counter.
The worker was threatened with a knife and the pair fled with cigarettes.
Anyone who witnessed any of the raids is asked to call Kirklees CID via 101.
