Vancouver police continue to investigate after extensively searching for a man they say is responsible for attacking a woman from behind on Friday night.

Around 11 p.m. PT the victim was assaulted in the area of West 48th Avenue and Oak Street but managed to fight off her attacker who eventually ran away. Police say was not physically injured.

"The motive for the attack appears sexual in nature," wrote Vancouver police in an e-mail to CBC News.

"Following an extensive search with a police dog and helicopter, the suspect was not located," the statement said adding that the investigation is ongoing.

Be cautious

Police are advising women to be cautious following the assault and say, "unfortunately due to circumstances," the victim was unable to provide a detailed description of her attacker, only that he is 5'8" to 5'10" tall with medium build.

In February police issued a public warning following two assaults in the Oakridge neighbourhood where two separate female victims were approached by a stranger.

Officers also issued another similar public warning in October, 2014 after three related sex assaults in the area.