At around 8.15pm on Sunday an 18-year-old man was walking from Fuller Slade to Wolverton, Milton Keynes.
He was in the underpass between Greenleys and Syward Row, when he was approached by three men, who demanded that he hand over his possessions. When the victim refused he was assaulted.
The victim received stab wounds to the legs, and also suffered a head injury. He was taken to hospital where he remains in a stable but non-life threatening condition.
The offenders took the victim’s IPhone 6.
The offenders are described as two white men, and a mixed race man. All three were wearing face coverings. One of the offenders was wearing a navy blue puffa jacket with the hood up and dark trousers. He had a skinny build.
Investigating officer, PC Kerry White of the Investigation Hub based at Milton Keynes police station, said: “We are carrying out a thorough investigation into this incident, which we believe to be an isolate incident.
“We are appealing for anyone who might have witnessed this robbery to please come forward.
“Additionally anyone who might have seen three men in the area around the time of the assault to come forward.”