A 16-year-old boy was chased into a corner, threatened with a brick and punched by thieves who stole his phone.
The teen was in playing fields off Hannon Road, Aylesbury, when two men approached him and asked him to empty his pockets.
He refused and ran away, but became trapped in a corner of the fields by the men.
At this point the victim noticed one of the thieves was carrying a brick.
One of the men demanded his phone. When the victim refused he was punched in the face.
The man asked again for the phone and the boy handed it over.
The crooks then ran off in the direction of Edinburgh Playing Fields.
The phone was an iPhone 5 with a cracked screen.
The incident was between 9.30pm and 10.30pm on Friday.
The first offender is white, around 6ft tall, 17 to 18 years old, of medium build, with a local accent and large nose. He was wearing a pale grey hooded top with the hood covering his face.
The second offender is white, around 6ft tall, 17 to 18 years and of medium build. He was also wearing a hooded top.
Anyone with information should contact PC Claire Busby on 101 or Crimestoppers anonymously on 0800 555 111.