Updated 06/24/13 – 9:38 a.m.

CHICAGO (CBS) — Police were warning residents of the posh Near North Side neighborhood about a man who has attacked two women in the past week.

The two attacks happened within about two blocks of each other in the span of a week.

Police said, around 5:40 a.m. on Sunday, a 26-year-old woman was walking in the 1000 block of North Dearborn Street, when a man ambushed her from behind, dragged her into an alley, and began sexually assaulting her.

A passerby scared off the attacker, and the victim was taken to a hospital.

On June 17, a woman who was walking in the 1100 block of North Clark Street reported a similar sexual assault. That woman also was approached from behind, dragged into an alley, and sexually assaulted.

The suspect in both attacks was described as an African American man with a dark complexion, between 35 and 45 years old, standing 5-foot-9 to 5-foot-10, and weighing 220 pounds. He was last seen wearing a dark blue tank top, white t-shirt, and blue jean shorts.

Watch & Listen LIVE