A 13-year-old was robbed of his bike in Semilong by a masked trio of young men brandishing a blade.
The incident happened between 3.35pm and 4pm on Friday, May 24, when the 13-year-old victim was confronted by three balaclava-wearing men in an alleyway alongside Northampton International Academy in Barrack Road.
One of the men threatened the boy with a knife, then took his bicycle and rode off.
Officers investigating the incident are appealing for any witnesses who may have seen the incident, people matching the description of the offenders, or anyone riding around or attempting to sell the distinctive stolen red mountain bike (pictured).
A spokeswoman for Northamptonshire Police said: "The first suspect is described as 5ft 9in, of stocky build. He wore a black tracksuit with a hood, which had writing down the arms and legs.
"The second suspect is described as white, aged 15-16, with black curly hair and no facial hair. He rode a black Carrera bicycle and wore a Kings Will Dream jacket in a silver-coloured reflective material with flags on the back and arms.
"The third suspect was a white male."
Anyone with information about the incident is asked to contact Northamptonshire Police on 101, or Crimestoppers in confidence on 0800 555111.