Police have arrested a man who they allege sexually assaulted a woman and left her naked and unconscious on a downtown street corner Tuesday.

Police said a passerby heard screams for help near Dundas Street East and Sherbourne Street at about 3 a.m. Tuesday morning.

When they arrived, police said they found a woman in her 50s who was naked and unconscious.

"She received serious, serious facial injuries," said police Cons. Tony Vella. "She was rushed to hospital. She remains in hospital in serious condition."

Police said they were not able to interview the woman as of Tuesday afternoon. They released a photo of a suspect taken from a security camera in the area.

Nathan Bumesi, 21, of Toronto, has been charged with choking, forcible confinement, aggravated assault, aggravated sexual assault and attempted murder.

He is scheduled to appear in court Wednesday morning at 10 a.m.