At around 12.05am on Sunday (23/6) two victims, a 34-year-old man and a 32-year-old woman, were walking home when they were approached by a black Audi A3 with tinted windows and two-tone silver alloy wheels on Howard Street.
The people inside the car sprayed an unknown liquid over the victims, before five people got out of the car and assaulted one of them.
The five offenders are described as black and Asian, between 18 and 25-years-old and wearing dark clothing.
The liquid was not a dangerous substance and did not cause any damage.
The 34-year-old victim sustained swelling to his face and received treatment at the John Radcliffe hospital. He has since been discharged.
Investigating officer PC Matthew Watson based at Cowley police station said: “This was a frightening incident for the victims, who were returning home from a music festival.
“The attack appears to of been completely unprovoked and I am appealing to anybody who was in the area in the early hours of Sunday morning who believes that they may have witnessed the incident or saw the black Audi A3 in the area to contact the 24-hour non-emergency number 101, quoting reference number 43190188944.
“If anybody has any CCTV or dash-cam footage from the area, please also get in touch.