A woman walking through Northampton was grabbed by a man who put her arm behind her back and stole her mobile phone.
The victim was walking along Bedford Road from the direction of the Avon building towards Northampton General Hospital when the attack happened.
She noticed four men had started walking beside her so she walked faster, but they kept pace with her.
One of the men then got in front of her, grabbed her left arm, put it behind her back and stole her mobile phone.
When the woman tried to follow the group of men, they ran away.
The men were all between 35 and 40-years-old, spoke with eastern European accents and were wearing yellow high-visibility work jackets. They were all about 5ft 6in and stocky.
The robbery happened between 3.15pm and 3.40pm on Wednesday, January 22.
Anyone with information can contact Northamptonshire Police on 101 or Crimestoppers anonymously on 0800 555 111.