Chicago police say a female worker, 42, at Afterwords New and Used Books on East Illinois near Wabash was attacked while closing the shop Tuesday night.
People in the area said they heard the woman screaming at approximately 10:15 p.m.
According to police, the suspect had come into the store earlier in the day. Then, as the victim was locking up the bookstore for the night, the suspect came back and claimed he forgot something.
That's when, allegedly, he pulled out a knife and forced his way inside.
Police say he took the woman to the back of the store, where she was sexually assaulted.
According to the Chicago Tribune, police say the woman then heard her husband in the store and screamed for help.
They say the husband began fighting with the attacker, suffering cuts to his head.
The husband then grabbed a bat and chased the attacker, who managed to grab keys off the counter, unlock the front door and run east on Illinois.
Although other neighborhood businesses saw police cars on Tuesday night, they weren't aware of what happened until Wednesday.
"Something like this should not be happening. It's a nice neighborhood. We've been here for a long time," said Saengchai Naegkhunthod, Star of Siam.
But some people who live and work in the area have been noticing changes in the neighborhood that they say gets desolate at night.
"It's getting to the point where at night after 8 p.m., I feel I can't leave unaccompanied in this area," said Lucia Malovany, neighbor.
The bookshop is located near the busy, downtown shopping district. Some people who live and work nearby say they have noticed changes in the neighborhood and wish someone would take action.
"I think the residents would complain, or the police would do something about it, but it doesn't seem like a concern, or maybe people are unaware of what's going on in this area," said Jeff Liska, who works nearby.
"We're hearing more and more activity in this area has been not safe. For me, as a woman, to be walking around without my boyfriend to accompany me to the grocery store that's four blocks away or the bookstore, it's a challenge for us," neighbor Lucia Malovany said.
Some others said they take precautions when they walk around.
"I generally have a walking buddy. I walk with somebody," said area worker Tonie Dowdy.
"I just always try and stay aware of my surroundings. When I walk around, I keep an eye out for anything that looks suspicious, if I feel like I'm in danger, I'll carry my keys in my hand," said Emily Snowberg, who also works nearby.
Chicago police have released a vague description of the suspect. Detectives returned to the scene Wednesday to continue their investigation.
They say the store does have signs warning of security cameras. Authorities say they will look at footage from those cameras to see if an image of the suspect was captured.
The woman was taken to a hospital and was recovering Wednesday.