A schoolgirl was sexually assaulted in a park in Long Hanborough on Sunday evening.
Police said the girl was approached by a man in the park off Roosevelt Road and attacked.
One of the girl's friends alerted people nearby and a man was held until police arrived.
Officers were called just after 5pm and the area was cordoned off to the public.
David Cromack, 21, had been riding his BMX in the skate park at about 5.30pm.
He said: “They asked me to leave saying there had been an incident in the park. They were checking all the exits. We saw about four or five police cars dotted around the village.”
Lynda Leach, deputy manager of Hanborough Pre-School, based in the nearby pavilion, said it was the first time she had known the park to have been shut.
She said: “My husband has lived here all his life and he said nothing like that has ever happened.”
A 23-year-old man who was arrested by police on suspicion of sexual assault was released on bail yesterday.
Det Insp Tom Brooks said they were appealing for anyone with more information to contact police on 101.
• Our top stories:
- Hundreds will gather as soldier killed in Iraq is repatriated
- Staff and students celebrate actress's big win at the Golden Globes
- Inquests opened into death of couple who died in cottage fire on Blenheim Palace estate
- Inquest opened into death of pensioner found in River Ock in Abingdon
- Man wearing beanie hat exposes himself to woman on city street
- Chain running Randolph Hotel in Oxford in 'best shape ever' after announcing £55m profit