A group of six youngsters were threatened and robbed in Wellingborough’s Swanspool Gardens.
Police are appealing for witnesses to the incident which took place when two men approached the group in the park in Doddington Road at about 1.20pm on Monday.
A police spokesman said: “One of the men grabbed an iPhone from one member of the group.
“He then threatened the others and stole two more phones and a bag.”
One of the robbers is described as a white man, in his 20s, with dark hair and slim build. He wore a grey hooded top with a white Nike logo on the front of the top, dark tracksuit bottoms, grey gloves and Nike trainers with black and yellow markings.
The second offender is white, also in his 20s, about 5ft 7in and of slim build. He had blonde/ginger hair and wore a grey hooded top.
Anyone with information about the robbery can call Northamptonshire Police on 101 or information can be given anonymously to Crimestoppers on 0800 555111.