Police described the woman as incredibly brave in coming forward to report the attack
Police are investigating a sex attack on a woman in Steyning, West Sussex, on Valentine's Day.
The 34-year-old, who lives in the town, was seriously assaulted in an alley between Middle Mead and Breach Close at about 20:00 GMT on Tuesday.
Police, who were alerted by the victim on Wednesday, say she was "incredibly brave" to come forward.
The suspect, who was wearing dark trousers and a hoodie, ran off in the direction of Coxham Lane.
Det Sgt Colin O'Hare, of Sussex Police, said: "We are offering [the woman] specialist support at this difficult time. We are yet to obtain a full account."
He added: "Crimes of this nature are extremely rare in this area, and we believe this to be an isolated incident. Local neighbourhood officers will be increasing high-visibility patrols."
