Police have shut a recreation ground in Cowley following an incident, with access to the site prohibited to members of the public.
Hollow Way Recreation Ground was closed by Thames Valley Police, according to reports.
Officers were first reported to have arrived late on Sunday, November 8.
Police vehicles and personnel were positioned across the area, while every entrance to the grounds was blocked.
Local residents have raised concerns about the visible presence of officers, although no further information about what happened had been made available.
The force was approached for a comment at approximately 7.30am on Monday.
The recreation ground is bordered by Wilkins Road, Marshall Road, Horspath Road and Hollow Way.
In addition to officers in uniform, investigators wearing plain clothes were observed working within the grounds and around its perimeter.