ROGERS PARK — Police are hunting for a man who sneaked up behind a woman in Rogers Park, knocked her out and raped her Wednesday evening, police said.

The attacker placed his hand over her mouth after he ambushed her at 6:40 p.m. Wednesday. The 31-year-old woman told police she smelled “an odd substance” and then lost consciousness.

It happened while the woman was walking in the 6600 block of North Clark Street, police said.

The woman woke up alone in an unfamiliar building after police said.

Police currently have no one in custody and detectives are investigating.

Police are looking to review surveillance footage along Clark Street to help identify the suspect. They are also hoping to find witnesses in the area.

Anyone with information can contact Area North detectives at 312-744-8261.