Detectives have released images of a man they want to speak to following robberies in Preston.
At about 9.30pm on Saturday, a man went into the Spar on Water lane and demanded money, but left empty handed.
Shortly afterwards a man fitting the same description entered KFC on Fishergate and made threats but again left empty handed.
A man also went into a store and a bank in Blackpool on Friday - leaving empty handed from the shop but fleeing the bank with £800.
The man claimed to have a firearm during the offences, but police said none has been seen.
The same offender is also believed to be responsible for a number of similar robberies in Greater Manchester.
Police want to speak to Peter James Thomas, 27, in connection with the offences.
Inquiries are underway to trace him and officers are warning people not to approach him but to contact police if they see him or have information on his whereabouts.
Sgt Mark Dickinson, of Blackpool CID, said: “We believe the same man is responsible for these offences and we would like to trace and speak to Peter James Thomas.
“I would appeal to anyone who sees him or knows where he might be to get in touch with us.”