Police said around 7:40 p.m. a man wearing a Chicago Police Department uniform, including a baseball cap, long-sleeve button-up shirt and reflective vest, as well as a surgical mask, entered a currency exchange inside the North Bridge shops in the 500 block of North Michigan Avenue.
The man approached a 22-year-old woman who worked there, implied he had a gun and announced a robbery, police said.
The woman gave the robber an unknown amount of cash inside a bag, and the man fled.
No injuries were reported, police said.
Police describe the suspect around 40 years old, about 6 ft. tall weighing 180 to 200 lbs.
No one is in custody.
An investigation by Area Central detectives is ongoing.