The robbery took place about 2 p.m. in the 5100-block of North Clark Street near Foster Avenue in Ravenswood, the FBI said.
The FBI released photos of the suspect, who they said walked into the bank and handed over a note demanding money.
The suspect is described as a person in his or her 20s; 5-feet, 6-inches to 5-feet, 7 inches tall; thin; and wearing black sunglasses, a black beanie, a red flannel sweatshirt. The suspect appeared to have short brown hair but may have had long hair tucked into a hat, the FBI said.
No injuries were reported in the incident.
RELATED: Northwest Side bank robbery suspect may have tried to rob another bank hours earlier: FBI
This was the third Chicago bank targeted by robbers in just a 24-hour period.
On Wednesday, there was a bank robbery in Irving Park and an attempted bank robbery in Bucktown.
Investigators have not tied this latest incident to the two Wednesday.
Tips can be reported at 312-421-6700 or tips.fbi.gov.
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