Thames Valley Police is appealing for witnesses following a robbery in Milton Keynes.
The incident occurred on the Redway between H5 and the flats on Ramsons Avenue at around 6.20pm on Saturday 3 December.
The victim, a boy in his teens, was walking when several offenders ran up to him.
They held the victim and threatened him with weapons before taking his iPhone and running off.
One of the offenders is described as being of medium build and was wearing a black balaclava.
All of the suspects were wearing a black puffer jacket and black joggers.
Investigating officer, Detective Constable James Schöpp based at Milton Keynes police station, said: “I am appealing for any witnesses to this incident to please get in touch.
“You can contact us by either making a report online or by calling 101, quoting reference number 43220544684.
“Alternatively, for 100% anonymity, you can also call the independent charity Crimestoppers on 0800 555 111."