A sex attacker fled after a 15-year-old girl's screams for help brought people out of their homes.
The teenager was pinned against a gate in an alleyway at the rear of Amberley Court in Banbury, Oxfordshire, and then sexually assaulted on Saturday.
She managed to struggle free and then ran into the court, where she called for help at 2230 BST, police said.
The man chased her and put his hands over her mouth but fled when people started to come out of their houses.
The man is white, 5ft 6 tall, about 18-19 years-old, of slim build with short dark hair.
He was wearing a black t-shirt and jeans.
PC Bobbie Nusspickel, of Thames Valley Police, said: "Although she wasn't physically hurt, the girl was obviously left in a distressed state following this attack."
Police are appealing for witnesses.