Police believe two 16-year-old girls raped and sexually assaulted in Cuttlebrook nature reserve, Thame, may have been seen with their attackers for up to an hour before the incident.
Three 16-year-old girls were in the park next to Southern Road recreation ground with two men between 8.30pm and 9.30pm on Saturday night.
One was later raped and the second sexually assaulted by one of the men.
He is described as white, around 5ft 9in tall while the second man is white, about 6ft tall with dark jelled hair.
Insp Jim O'Ryan said police will carry out extra patrols in the area but called for people to be cautious but not alarmed.
Anyone with information should contact police on 08458 505505 or speak anonymously to Crimestoppers on 0800 555111.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article