Thames Valley Police is appealing for witnesses to a robbery in the grounds of the Stantonbury Campus.
The two victims, boys aged 16 and 15, were approached by two men close to the artificial football pitch at around 12.30pm last Tuesday.
The men asked if they wanted to buy ‘weed’ and then attacked them, pushing one of them to the ground and then stealing a bag from the 15-year-old. His bag contained an HTC Wildfire mobile phone, school planner, bus pass and phone charger.
The other boy was forced to remove property from his bag but nothing was stolen before the men ran off.
PC Mark Burgess, from Milton Keynes CID, said: “Both victims have reported that one of the offenders had a knife and that it was used to threaten them.
“This incident happened in the middle of the day and I am keen to hear from anyone who witnessed what happened or who has any information about who may be responsible.”
Anyone with any information should contact PC Burgess via the 24-hour Police Enquiry Centre on 101
Alternatively, if you do not want to speak to police, or leave your name, please contact the Crimestoppers charity on 0800 555 111.
A 14-year-old boy and an 18-year-old man have been arrested as part of the investigation into this incident. They have been released on bail to return to Milton Keynes police station on January 16.