The incident occurred in the Yonge Street and Canyon Hill Avenue area at about 12:30 a.m.
Police say the victim was taken to hospital where she was treated for injuries.
So far, police have revealed that the male suspect wore a grey ski mask and had dark-coloured clothing on.
On Thursday, police sent in a search-and-rescue team to comb through a nearby field.
Anyone with information is asked to contact investigators at 1-866-876-5423, ext. 7071.
Information can also be passed on through Crime Stoppers at 1-800-222-8477.Suggest a correction