An 18-year-old woman said she was sexually assaulted in an apartment building about 9:47 p.m. in the 400 block of North Kedzie, Chicago police said.
The partially clothed woman reached out to a neighbor and requested an ambulance, police said.
She was transported to Swedish Hospital where she was listed in fair condition, according to police.
The suspect fled the building on foot, according to police.
No one is in custody as Area Five detectives continue to investigate.