UPDATED 08/10/12 6:08 a.m.

YORKVILLE, Ill. (CBS) — A woman’s claims that she was sexually assaulted by a man impersonating a police officer are unfounded, the Kendall County Sheriff’s Department said Thursday.

Police earlier this week said a 33-year-old woman was pulled over by a fake cop Tuesday evening on a roadside in unincorporated Plano and sexually assaulted at gunpoint. The woman said the suspect had been driving a Ford Crown Victoria with a blue emergency light activated on the front of the car.

The woman said the suspect, wearing a police, fire or security uniform, pulled a mask over his face and pointed a handgun at her. She said she was ordered to get out of her car and walk to a cornfield just off Griswold Springs Road where she was driving.

The woman said she was beaten and sexually assaulted in the cornfield before the offender fled. She did receive treatment in an area hospital.

The alleged incident sent shockwaves through the exurban region.

“Something happening in this little itty bitty town is just very shocking, and it’s very nerve-wracking, and it’s very devastating,” Desiree Dubson said after the attack, which she said was the talk of the town in Plano Wednesday morning. Dubson said she wouldn’t even take Griswold Springs Road anymore because of the alleged incident.

But on Thursday evening, police said the whole thing had been a hoax.

“It was determined that an assault did not occur and there was no police impersonator involved,” the sheriff’s office said in a news release Thursday. “There is no known threat to public safety, but we still urge the public to use caution.”

The Kendall County State’s Attorney’s Office is reviewing the “incident,” the release said. Further details were not given.

Filing a false police report can result in criminal charges, fines and prison time. The sheriff’s department used resources to alert the public and investigate the case.

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