A man in his 20s has been gang raped near a bridge in Milton Keynes.
Police are looking for four to six men after the attack on the Redway at the rear of Lamberts Croft, Greenleys, in the early hours of Monday.
The man was assaulted and raped by the men, said Thames Valley Police.
Det Insp Nick Glister said: "I would like to reassure people that we are treating this report very seriously and a team of detectives is working to gather evidence."
"We are keen to hear from anyone who witnessed the incident or any suspicious activity in the area, or has any other information which may assist us with our investigation.
"We appreciate that this incident is likely to cause concern in the community and we ask anyone with any concerns to contact their neighbourhood team via 101."
Anyone who witnessed any suspicious activity in the area or has any other information is asked to call Thames Valley Police.
