Police descended on Birkenhead town centre after claims a man had pulled a knife on a young mum with a baby and tried to mug her.
A large police cordon was set up outside Birkenhead Market and The Pyramids shopping centre just before lunchtime.
An entrance to the Pyramids was closed while enquiries got under way.
Police said officers were called just before 11.30am to a report of a man who had allegedly behaved anti-socially in the premises, and then produced a knife while being escorted away by security staff.
Officers attended and the man was detained a short time later.
A 37-year-old man has been arrested on suspicion of possession of an offensive weapon and a public order offence. He was taken into custody for questioning.
A police spokesperson added: "There were no reports the knife was used to harm anyone, and enquiries into the incident are ongoing."
Police cordoned off a large area outside and the Pyramids this lunchtime while they carried out enquiries.
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It was suggested on social media a man with a knife had threatened a young mum pushing a baby in a pram.
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Witnesses reported seeing a man running up a service road used by the market and shopping centre before he was arrested by officers.
