The incident occurred at a house on Baker Street, in the Clifton area, at about 2.15am today (Tuesday 9 July 2013).
A man wearing a hooded top was confronted by the occupier in a first floor bedroom where he then attacked her with an unknown implement, causing deep cuts to her head and an ear.
Various items of property from both upstairs and downstairs rooms were stolen before the man made off via the back door of the house.
The victim, who is aged in her 50s, was able to telephone for emergency assistance. She was taken by ambulance to York District Hospital where she is receiving treatment for serious but not life-threatening injuries.
Extensive police enquires began immediately to locate the suspect and to determine the full circumstances surrounding the incident.
A specialist police search team is continuing to work in the neighbourhood, along with crime scene investigators who are examining the property to support the investigation.
Officers from the York North Safer Neighbourhood Team are also carrying out high-visibility patrols in the area to help reassure the local community while the investigation is ongoing.
Detective Chief Inspector Nigel Costello, of North Yorkshire Police’s Major Crime Unit, said:
This is a very disturbing incident and we are doing everything we can to support the victim and to bring the offender to justice.
To assist the investigation, we are appealing to anyone with any information to come forward to the police as a matter of urgency.
We need to know about any suspicious behaviour or sighting of individuals in the Baker Street area of Clifton during the early hours of Tuesday morning.
If anyone thinks they can help to identify the suspect, please do the right thing and pass a name to the police in confidence.
If you would prefer to remain anonymous, you can still help the investigation by contacting Crimestoppers.
As a community, we simply will not tolerate this type of violent, criminal behaviour. Residents can be assured that these type of offences are extremely rare and we will not rest until the suspect is in custody.
If you can help the investigation, please contact North Yorkshire Police on 101 – select option 1 – and pass information to the Force Control Room.
If you would prefer not to give your name, call Crimestoppers on 0800 555 111.
When passing information about this incident, please quote the reference NYP-09072013-0030