A 72-year-old man suffered what appears to be a serious head injury. He was taken by ambulance to hospital where he is receiving emergency treatment.
A 24-year-old man has been arrested in connection with the incident and is being questioned in custody.
Witnesses are asked to call North Yorkshire Police on 101, select option 1, and speak to the Force Control Room.
Or call Crimestoppers anonymously on 0800 555111.
Please quote reference NYP-11062015-0379 when providing information about this incident.