EVANSTON, Ill. (CBS) — A woman was sexually assaulted in an alley earlier this week as she walked a dog just a few blocks north of the Northwestern University campus in Evanston.

The university issued a security alert in the wake of the attack in an alley off the 700 block of Central Street, close to Orrington Avenue. The victim is not affiliated with Northwestern.

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Between 10 p.m. and midnight Monday, the woman was walking a dog when she was confronted by a man who displayed a gun and sexually assaulted her, according to the alert.

“The victim reported it initially to a co-worker, and the co-worker notified police,” Evanston Police Cmdr. Jay Parrott said.

The 23-year-old Chicago woman was in the area for her job, which is walking dogs, Parrott said.

She was examined at a hospital, where she was treated and released, he said.

The offender was described as a white man, 30-50 years old and 5-foot-10 to 6 feet, wearing a dark knit cap, dark coat and dark pants, the alert said.

Even though the victim was not affiliated with Northwestern, Parrott said the attack was not only near the campus, but also just about a block from the home of the university president.

Police have had no previous reports of attacks in that area, he said, and no witnesses have yet contacted police.

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The incident remains under investigation and anyone with information should call police at (847) 866-5000.

Northwestern University Police remind students and staff to report suspicious people and activities to university or Evanston police by dialing 911, or by using one of the blue-light emergency phones on campus.

This is the second sexual assault that has made the headlines in Evanston in as many weeks. Around 1:55 p.m. March 5, a woman called police and said reported that she had been sexually assaulted in broad daylight in the 1900 block of Dewey Avenue, just north of Emerson Street.

The woman, a 19-year-old Evanston resident, had gotten off a Chicago Transit Authority bus at Emerson Street and Dodge Avenue, and her rapist followed her off the same bus, police said.

Upon reaching the residential block of Dewey Avenue, the rapist grabbed the woman and slammed her to the ground between two houses, police said. He then ripped off the woman’s clothing and had forcible sexual intercourse with her, police said.

Marlow S. Land, 24, of the 200 block of North Latrobe Avenue in the South Austin neighborhood, was charged with three counts of criminal sexual assault, after police say he admitted to the crime.

The Sun-Times Media Wire contributed to this report.

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