Two women were sexually assaulted in an early morning attack near a playground in south-east London, police say.
The attack happened on Plumstead Common, near Plumstead Adventure Play Centre, at about 1am on Thursday.
Residents said on social media that a huge area of the common was taped off by police as forensic officers combed the area for evidence.
Scotland Yard said no one has been arrested following the incident.
A police spokesman added: “A crime scene is in place at this time while an investigation is carried out.
“Specialist officers are supporting the victims. Enquires continue.”
The age of the victims are not currently known.
Last week a teenager was rushed to hospital after a he was stabbed outside a convenience store on Plumstead Common Road, a short distance from Thursday's attack.