A man wearing dark tracksuit bottoms approached two women in Northampton while waving a knife.
The incident happened in Farmfield Court, Thorplands, sometime between 4.45pm and 6pm last Saturday (August 26), Northamptonshire Police today revealed.
A spokeswoman for Northamptonshire Police said: "The offender was white, slim and aged in his late 20s. He was 5ft 5in-5ft 7in with short mousey blonde hair and a short blonde moustache. He was wearing dark tracksuit bottoms and a light- coloured T-shirt."
Anyone with information should call Northamptonshire Police on 101 or Crimestoppers, in confidence, on 0800 555111.