Police in England are appealing for information about the sexual assault of a 58-year-old woman as she walked her dog.
The incident took place in a grassed area near Church Street, in Workington, Cumbria, between 10.15pm and 10.30pm on Friday.
The victim received serious head injuries during the attack and was taken to Cumberland Infirmary in Carlisle.
An 18-year-old man from Workington has been arrested and is being questioned in custody, said Cumbria Police.
Detective Dave Pattinson said: "It is believed that the attacker may have been disturbed by a person walking in the area, so we are urging anyone in the area at the time, or anyone who may have any information to call us - no matter how trivial the information may seem it could be important for our investigation.
"This is a serious assault, and I am appealing to the local community to help us with our ongoing investigation. The victim is being supported by specially trained professionals at this difficult time."
Anyone with any information should call Cumbria Police on 101 and ask to speak to an officer from West Cumbria CID, or call Crimestoppers anonymously on 0800 555 111.