It happened at the Rockford Bell Credit Union in the 4200 block of Perryville.
A suspect entered the building, fired a gunshot then got away with an undisclosed amount of money. There were no injuries.
The gunman is described as a black male, 150 pounds, wearing dark clothing and blue jeans. He was last seen in a red, 4-door Chevy Impala with Nebraska plates.
Anyone with information is asked to call Loves Park Police.