A 15-year-old boy was stabbed at Fulbridge Road Recreation Ground and taken to Peterborough City Hospital.
Forensic officers were at the scene yesterday evening following the serious assault which left the teenager with serious but not life-threatening injuries.
A Cambridgeshire police spokesman said: “We are currently investigating a serious assault that happened in Peterborough yesterday (Thursday, December 28).
“A 15-year-old boy was stabbed in Fulbridge Road and has been taken to Peterborough City Hospital with serious but not life-threatening injuries.
“At this stage no arrests have been made.”
The recreation ground was cordoned off by police last night, with the cordon remaining in place the following morning.
Scenes of Crime Officers were seen searching a play area at the recreation ground, which is located just off Shakespeare Avenue in New England.
Asked whether the stabbing might be gang related, the police spokesman said: "We are waiting to speak to the victim to understand what happened but at this stage it is being treated as an isolated incident."
Anyone with information is asked to call police on 101.