North Yorkshire Police were called by the Ambulance Service at around 2.35pm on Monday 17 September after a three-year-old girl suffered serious injuries in a play area at York College, on Sim Balk Lane.
The girl was taken to York District Hospital, where sadly she was pronounced dead.
The scene is currently cordoned off as officers investigate the incident.
At this stage, police do not believe there are any suspicious circumstances and it appears that the girl has become entangled in a piece of play equipment.
The police are carrying out an investigation into the incident to establish exactly what happened and would like anyone who was in the area at the time to contact them on 101.
Ofsted and the Health and Safety Executive have been informed.
The nursery will be closed tomorrow (Tuesday 18 September 2012).
6.10pm - 17 September 2012
Update: The family of Lydia Bishop, aged three, who died in a tragic accident at York College's day nursery on Monday 17 September 2012, have released a photograph of her.
Lydia's parents, Brad and Rebecca, have requested that the media respect their privacy at this extremely difficult time.
Detective Chief Inspector Nigel Costello, of York Protecting Vulnerable Person's Unit, said: "This was an extremely tragic accident which unfortunately happened during Lydia's first day at nursery.
"Her family are understandably very distressed and are being supported by specially trained police officers as they try to come to terms with their loss.
"Officers are currently investigating the circumstances surrounding this incident with various other agencies to try and establish how this tragic event occurred."
4.19pm - 18 September 2012