Humberside police are appealing for witnesses after cash was stolen from a 32-year-old man in Bridlington at around 1.45pm on Tuesday 4 July.
It was reported that the victim was walking down an alleyway between Holyrood Avenue and Haslemere Avenue in Bridlington when he was approached by four men on bikes.
The men allegedly threatened the man with a craft type knife, before stealing a £20 note and cycling away. The victim suffered minor injuries in the incident.
The first man is described as being white, of stocky build, around 5ft 11ins tall, with brown eyes. He was wearing dark tracksuit bottoms, a waterproof jacket with a hood pulled right down to just above his eyes and a grey and black scarf covering the bottom half of his face.
The second was also white, around 5ft 4ins tall and of larger build. He was wearing black jeans and a dark hoodie with the hood pulled up and tied to cover most of his face.
The third man was white, 5ft 11ins tall and of skinny build with fair hair. He was wearing dark tracksuit bottoms and a dark hoodie with a logo on.
The last man was white, of skinny build and wearing navy tracksuit bottoms and a dark jacket.
If you witnessed the incident please call 101 quoting log 341 of 04/07/17 or Crimestoppers anonymously on 0800 555 111.