CHICAGO (CBS) — A woman was sexually assaulted and robbed while walking to the Red Line on the South Side early Sunday morning.

Police issued a community alert in the Auburn Gresham neighborhood after the 57-year-old woman was attacked at knifepoint.

The woman was walking to the Red Line under the 78th Street viaduct between Wallace and Fielding avenues around 3:30 a.m. Sunday, when a masked man walked up and sexually assaulted her at knifepoint.

Police said the rapist threatened to kill her, and stole her cash, ID, credit cards, and debit cards.

“It’s very scary, knowing that it’s right down the street, a block away,” Auburn Gresham resident Marcus Quinn said. “That could have been my significant other going out early in the morning, because we leave out early in the morning to go to work.”

Keisha, who said she’s lived in Auburn Gresham for 25 years, said she’s never had any problems, so it’s shocking to hear about this kind of attack in the neighborhood.

“I walk that way sometimes when I’m leaving my friend’s house. So someone to do that in this quiet neighborhood is, like, wow,” she said. “We walk there, walk back, and so to see our neighborhood changing, hearing things like that, that’s crazy to me.”

Authorities had only a vague description of the rapist, who was wearing a red ski mask, blue denim jacket with white sherpa fur collar, and black pants. He was wielding a 6- to 8-inch knife with a brass knuckle grip.

Police urged people to be aware of their surroundings, and call police right away if they see anything suspicious. Anyone with information about the attack should call Area South detectives at 312-747-8271.