Four women were assaulted in Sale town centre.
At around 1.30am on Saturday 15 September 2012, the women, aged in their 20s, were on School Road, Sale and were approached by a group of people.
Without provocation, the victims were attacked.
A 23-year-old woman was left with a broken leg and cuts to the head. The other victims suffered cuts and bruises.
It is believed the group was made up of three white men and a woman of mixed race.
It is also thought they had either got out or were near a Ford Ka at the time of the assault.
Detective Inspector Deborah Oakes from Trafford CID said: “This was a violent and unprovoked attack on a group of girls who were enjoying a night out with friends.
“We are investigating the circumstances surrounding the assault and would ask anyone who witnessed the incident or saw a Ford Ka in the area at the time of the attack, to contact police as soon as possible.”
Anyone with information should phone police on 0161 856 7669 or the independent charity Crimestoppers, anonymously, on 0800 555 111.