A woman who was subjected to a "ferocious" rape by a stranger while walking her dog feared she would die before passersby intervened, police have said.
The victim, who was in her 20s, was grabbed by 22-year-old Brandon Woolven as she walked in woodland near Pontefract Road, Barnsley, on the morning of Thursday 14 April.
He dragged her into a more secluded area before assaulting and raping her.
Two joggers saw what was happening and intervened, pulling him away from the victim.
One of them was assaulted, but managed to detain Woolven until police arrived and arrested him.
Det Con Becky Robinson, of Barnsley CID, said: "I have been working as a police officer for 16 years now and in all my service have never been faced with an investigation quite as horrifying as this one.
"Woolven attacked his victim at random, in broad daylight, and subjected her to the most brutal and sustained physical and sexual abuse imaginable.
"She has since told us that she believes that without the intervention of the two passers-by, she would have been killed – such was the ferocity of Woolven’s assault.
"This was a truly terrifying incident and I want to wholeheartedly commend the victim in this case for her unerring support of the police investigation and for the immense bravery she has shown throughout."
The officer praised the "bravery and heroism" of the witnesses, who were left injured.
Woolven, of no fixed address but who comes from Brighton, was described as "a truly dangerous individual". He admitted rape, two counts of sexual assault and two counts of assault occasioning actual bodily harm and was jailed for 11-and-a-half years. He was also handed an indefinite Sexual Harm Prevention Order.
Det Con Robinson added: "The victim in this case continues to recover from the physical and psychological injuries she suffered as a result of this attack and I hope that with the sentence passed today, she is able to take another step forward on her journey to recovery."