An 18-year-old woman was grabbed, forced to the ground and sexually assaulted after walking from the GO bus terminal in Newmarket on Friday.
Police said the woman was walking westbound on a pathway that runs parallel to Davis Drive, from the GO bus terminal, towards Crossland Gate around 3 a.m.
The female was allegedly approached by a man who is being described as about five-foot-nine, has a lean build, 30 to 40 years old and was wearing a covering over his face.
A man interrupted the assault and interacted with the victim but left the scene prior to police arriving. Investigators are asking that this man come forward and contact police immediately.
Police said the woman sustained minor injuries and was taken to hospital.
Police are asking anyone with information to contact them.