A teen who ran to the aid of a woman being attacked at a campground on New Year's Day has described her "horrific" screams.
Noam Whiteside, 18, said he returned from the Rhythm and Vines music festival to his tent at Gisborne's A&P Showgrounds when he heard a woman screaming for help just after midnight.
"They were the most horrific screams I've ever heard," he said.
The trainee pilot said he ran to the woman's tent where he saw a man on top of her.
"I yelled out and he bolted, so I chased after him."
The offender made off in a light-coloured SUV which was seen entering the premises around midnight. There were at least two people in the vehicle at the time, police said.
Police said the 24-year-old victim was asleep in her tent when the unknown man entered and began a sexually motivated attack.
Whiteside said he returned to comfort the woman, who was standing near her tent, before rounding up a group of friends also staying at the campsite, to search for the offender.
"The victim reported biting his hand and arm. It is possible he has visible bite marks."
Smith described the assault as very serious and a traumatic experience for the young woman.
"The victim has received medical attention and given detailed information in regards to the incident.
"She is being supported by friends and family, victim support and police. The victim is not from Gisborne and has since returned home."
Anyone who may have seen the vehicle or has any information - no matter how small - that may be helpful to authorities investigating the incident is being urged to contact police immediately.
The incident follows similar attacks on young women or girls in the last week.