Police are appealing for witnesses following four robberies on Saturday night at shops in Cullingworth and Oxenhope and Halifax.
The gang raided Co-op mini markets in Greenside Lane, Cullingworth, and Station Road, Oxenhope, before heading to Halifax to finish their spree.
It is believed the suspects were driving a Volkswagen Golf with false number plates and have visited two Bradford petrol stations beforehand to steal fuel.
Detective Inspector Neil Benstead said: "In all four offences, two people dressed in balaclavas and armed with hammers have entered the businesses and demanded cash from tills.
"Thankfully none of the cashiers were injured but this was understandably a frightening ordeal for them and we are making extensive enquiries to locate those responsible.
"The incidents are being officially linked and we are keen to speak to anyone who witnessed any part of this crime spree or who may have information about those responsible.
"The suspects and vehicle had earlier attended at two petrol stations in Bradford, one on Thornton Road, Thornton, and one on Haworth Road, Bradford, in an attempt to steal petrol. They were successful at the Howarth Road petrol station.
"The suspects were using a dark coloured, possibly blue or black, Volkswagen Golf with registration number FR12 UFW. We believe this vehicle was displaying false number plates.
"We would also urge anyone with information about the movements of this vehicle or its current whereabouts to get in contact."
The shops raided were at Greenside Lane, Cullingworth, at 8.38pm; Station Road, Oxenhope, Keighley, at 8.51pm; Park Drive, Halifax at 9.25pm; and Highroad Well Lane, Halifax at 9.31pm.
Anyone with information is asked to call Bradford CID on 101.