Officers were called after receiving a report of a boy being robbed by three men wearing face masks and brandishing a knife.
The incident took place at around 3.10pm on Monday in the alleyway leading from Albert Road to Lynchwood Road.
A 20-year-old man from Feltham, a 21-year-old from West Drayton and a 20-year-old man from Hounslow have all been arrested.
If you witnessed the incident, have CCTV, dashcam, or have any relevant information, please contact us quoting PR/45240074445 via 101.