A woman was raped in an alleyway shortly after leaving a nightclub, police have said.
The 20-year-old had walked into the side street after coming out of the Moo Moo Clubrooms in High Street, Banbury, at about 23:15 GMT on Friday.
She described her attacker as a white man with a moustache.
Thames Valley Police said its enquiries were at an early stage and issued an appeal for information from any witnesses.
It said there would be an increased police presence in the town centre as investigations continued.