Police were called just after 4.30pm yesterday to an address in Alness Drive in the Woodthorpe area of the city.
Officers attended and upon visiting a scene nearby, they found a seven-year-old girl with life-threatening injuries.
Ambulance attended and the girl was taken to York District Hospital,
where she sadly died of her injuries a short time later.
A 15-year-old girl has been arrested in connection with the incident. She remains in police custody for questioning.
Police officers remain at the scene while the investigation to establish the full circumstances surrounding the death of the girl continues.