A 15-year-old boy had his mountain bike stolen in a robbery on Friday night in Northampton.
The teenager was riding his bike through an alleyway between Longland Road and Northwood Road, Eastfield, just after 9pm on Friday, November 10.
As he approached a grassed area he was stopped by a group of around four men who demanded he hand over his bike. One of the offenders threatened him while holding a machete.
All of the offenders were men, around 6ft, of medium build and had their faces covered. All wore dark clothing with hoods up and are believed to have been adults.
The man who threatened the teenager spoke with a London accent.
Officers would like to speak to anyone who may have witnessed this incident or who may have any information regarding it.
Witnesses or anyone who may have any information about this incident can call police on 101 or Crimestoppers anonymously on 0800 555 111.