CHICAGO (WLS) -- Chicago police are looking for a man who they say sexually assaulted a woman while she was walking in the city's Rogers Park neighborhood Wednesday afternoon.The 31-year-old victim told police she was walking southbound on 6600-block of North Clark Street from North Shore when a man came up behind her and covered her nose and mouth with some sort of substance that made her lose consciousness.The victim said she later woke up alone in an unknown building after being sexually assaulted.The suspect is described as a black or Hispanic man.Police said it is unknown which direction he fled after the incident."There are a lot of people walking around here and like, it's kinda crowded so it is possible for someone to do that in a crowd," said Santi Kami who lives nearby."It's scary and makes other people, or girls, not want to, like, walk around alone," said Samikchhya Gajmer, who also lives in the neighborhood.Some people in the neighborhood said this incident is particularly alarming since there were two murders that happened in the area, about a mile from the scene of the crime, that are still unsolved.Police are looking for both surveillance video and any witnesses that may help them track down the perpetrator.If you have any information, contact Area North detectives at (312) 744-8261.