A masked robber grabbed a female member of staff and held a kitchen knife to her back during a terrifying raid at a bookmaker's shop in Hull.
After pouncing on the woman at Coral in Hawthorne Avenue on Saturday night, he told her colleague behind the counter to hand over cash.
He then fled with the money in a plastic bag leaving the two women shaken but uninjured.
The robber was 6ft 2in and wore a dark jacket and dark trousers.
He was wearing a blue balaclava and spoke with a local accent, police said.