At around 5.15pm, an incident took place in the play area close to Jenkinson Grove, Armthorpe where a 15-year-old girl suffered a stab wound to her stomach.
She was taken to hospital where she remains today with non-life threatening injuries.
Two girls, aged 14 and 15-years-old, were arrested shortly after the incident.
Inspector Mark Payling for the East Neighbourhood Policing Team said: “We understand the concern the report of this incident will have caused the local community.
“I want to offer my reassurance that we are treating it with the utmost priority to be able to understand the circumstances and put sufficient measures in place.
“Additional patrols will be in the area over the coming evenings to provide reassurance to the local community.
“I would encourage anyone with concerns in their area to please call police in 101.”