A man was threatened with a knife as he worked in a barber's shop.
This happened when three men are reported to have entered Cut Fellas, on Clifton Green, York, at 7pm yesterday.
They demanded money and the member of staff handed over a "large amount" of cash.
The victim was in the process of closing the shop and pursued one of the men around the Clifton Green area as they made off on foot.
North Yorkshire Police believe the suspects then used a vehicle to head north out of York on the A19.
Officers have appealed for witnesses to come forward.
One of the men is described as aged 20 to 22, skinny build and between 5ft 5ins and 5ft 7ins tall. He had stubble and wore blue denim jeans and trainers. He is believed to be of British origin.
The second is 25 to 30 years old and skinny. He is around 5ft 7ins tall, with a thick beard, a very thin face and short black hair. He is described as being of Kurdish origin.
The third man is believed to be around the same age as the second. He is 5ft 9ins tall and a stocky build. He had stubble, dark curly hair and wore a grey hoodie with the hood up. He is also described as being of Kurdish origin.
Police attended the scene after receiving a call at around 7.20pm yesterday and have launched a full investigation, which includes carrying out enquiries in the area, forensic tests and reviewing CCTV.
Nobody was seriously injured in the incident and no customers were in the shop at the time.
To share information, please call North Yorkshire Police on 101, select option 2 and ask for York Serious Crime Team.