A youth has been charged in the sexual assault of a 62-year-old woman in downtown Edmonton Tuesday night.

The woman was assaulted in the area of 93rd Street and 103rd Avenue while walking home from work around 9:45 p.m.

Two hours later, neighbours found her lying by a fence outside their house, unconscious and bleeding heavily around her face and head. She was also suffering from hypothermia.

The woman was taken to hospital where police say she remains in a "medically guarded" condition.

"In the two years that I've been the supervising member in the sexual assault section, I can't recall an event this violent involving a youth,"  Staff Sgt. Deb Jolly said.

A 17-year-old male was arrested Wednesday afternoon and charged with aggravated sexual assault and robbery. He will appear in youth court on Friday.

As far as police can tell, the complainant and the accused do not know each other. Jolly says it isn't common for sexual assaults to be committed by strangers.