A 44-year-old is in custody in connection with robbery at a cash machine in Chester.
Cheshire Police arrested the man, who is from Deeside, on Wednesday night (May 11).
The attack happened in Brook Street just after 11.30am on Tuesday.
A 19-year-old victim was trying to take money out of an ATM when the offender sneaked up behind him.
After threatening the teenager with a small knife, the offender swiped his cash and ran off towards Egerton Street.
DS Nick Henderson said: “I would like to reassure the public that this is an isolated incident and we are committed to doing all that we can to trace the person responsible.
“Thankfully the victim was not injured as a result of the attack, although he has been left traumatised by his ordeal."
Anyone who can help is asked to contact Cheshire Police on 101 quoting incident number 297 of May 9.
Information can also be passed anonymously to Crimestoppers on 0800 555 111 .
