The suspect was driving a car similar to a police cruiser that was equipped with flashing lights.
The victim pulled over then a masked man carrying a gun approached her vehicle and ordered her to get out.
The attack took place Tuesday evening near the intersection of Griswold Springs Road and Little Rock Road in Kendall County.
Police are very concerned for the public safety and that is because the attacker used the ruse anybody could fall for, impersonating a police officer.
"This is an isolated incident but we want to safeguard the public," Kendall County Det. Sgt. Joe Jasnosz said.
Their main concern is nobody else fall prey to a police impersonator who on Tuesday sexually assaulted a 33-year-old woman. She was driving alone.
The woman noticed a vehicle behind her being a dark blue Ford Crown Victoria with the red and blue light flashing in the windshield of the vehicle.
He was wearing some kind of uniform, walked up to the car, pulled a mask out, displayed a weapon.
The attack happened not 200 yards from his property.
"It is astounding to me the things that are happening,"
It may look like there is little other than corn fields around, but it is a pretty busy road. That is why police are calling on all motorists to call 911 if they remember seeing the impersonator's vehicle stopped along the road.
"We are looking for information that could have that emergency light visible right in that windshield," Jasnosz said. "That is what we are seeking information on. Anybody that has a description of a driver, license plate number, those are the leads we are looking for to drive our investigation."
Anybody that believes they might be being pulled over by a police impersonator in an unmarked vehicle is to immediately call 911 and not stop until they get to a more public location.
In Kendall County sheriff deputies use Chevy Impalas, not Crown Victorias.