A woman was raped by two men after being followed along a road in the early hours of the morning.
A 19-year-old woman was approached by two men, who she did not know, as she walked along Lake Road, Portsmouth, just before 01:00 BST.
They then followed her to Turner Road where the “very distressing” attack took place, Hampshire Constabulary said.
The force is appealing for CCTV and dashcam footage.
The woman is receiving support from specialist officers. No arrests have been made.
Det Insp Emma Crute said: “This has been a very distressing incident for the victim and I want to urge anyone who may be able to assist our inquiries to get in contact with us as soon as possible.”
It was believed the men may have been disturbed by a car driving close by, she added.
“I am also keen to speak with anyone who may have seen two men acting suspiciously or hanging around in the hour before in Lake Road, or anyone who drove through this area or Turner Road between midnight and 01:00 BST, and has dash cam footage,” she continued.