Updated 07/09/13 – 9:42 p.m.

CHICAGO (CBS) — Police were warning women in a trendy North Side neighborhood to take extra precautions, after a woman was brutally attacked while waiting for a bus.

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The woman was waiting at a bus stop in the 1000 block of North Western Avenue in the West Town area, around 5 a.m. Monday, when a man grabbed her and dragged her to a nearby gangway.

The man then beat her and sexually assaulted her, according to police.

CBS 2’s Susanna Song spoke to a witness who heard the victim’s screams, and called for help right away.

Maria, who didn’t want to reveal her last name to protect her identity, said she was up around 5 a.m. Monday, when she heard the victim’s shrieks.

“These screams did not sound like they were a fight, but two people. It was someone in danger,” she said. “I didn’t want to raise my shade high enough, or put my head out enough. … I wanted to protect my safety, too. I had no idea what I was going to be looking at if I did see something.”

But the screams were loud enough for her to grab her cell phone, and text police at the new emergency crime line. A few minutes later, police and paramedics arrived.

Maria said the 20-year-old victim was transported to the hospital.

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“As a female, I think it’s always going to strike you in a different way, but this hit home, for me, you know? Because I heard it, and … it could have happened to me.”

For Maria Sotelo, who also lives nearby, public transportation is all she can afford.

“I’m scared now, because I have to travel, commute, go to work. I have to work the second shift, as a single parent,” Sotelo said. She said it’s not uncommon for her to have to take the bus at night.

Both women said they’ll try and be extra cautious, but that might not always be enough.

“You see somebody getting close to you, just cross the street,” Sotelo said.

Chicago Police taped off part of the gas station, kitty corner from the crime. An evidence tech dusted for fingerprints in the middle of a station littered with security cameras pointed in almost every direction. Police wouldn’t say if the cameras captured the attacker or the attack.

Area Central detectives have issued a community alert, warning residents and commuters of the attack.

Police had only a vague description of the suspect. He was described as African American, 19 to 26 years old, 5-foot-9 to 5-foot-10, and 160 to 180 pounds. He was clean shaven, with a dark brown complexion, and was wearing a green t-shirt, green shorts, black shoes, a black do-rag, and diamond stud earrings in both ears.

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Police advised local residents to walk in pairs or groups, pay attention to their surroundings, report any suspicious activity immediately, and remain calm if confronted by an assailant. In case of an attack, police said victims should call 911 right away, try to remember any unique physical characteristics of their attacker, and never pursue a fleeing assailant.