Detective Superintendent Heather Pearson, of North Yorkshire Police said:
As a result of the incident a criminal investigation is underway. Officers are deployed to support the 83-year-old woman who is being cared for by family members.
"A number of enquiries are ongoing including tracing people who can assist.
"Detectives would like to speak to anyone who can assist in establishing a picture of the events leading up to the assault and ask that they contact York CID as soon as possible."
Any witnesses are being asked to contact North Yorkshire Police on 101.
More top news
The plan would leave steelworkers worse off in retirement - but not as worse off as those in other pension schemes.
Ministers are considering changes to pension laws in an attempt to persuade Tata abandon its planned sell-off.
From Thursday, "legal highs" are to be legal no more, with the Psychoactive Substances Act coming into force. But what does it all mean?