A 15-year-old boy has been charged with raping a 47-year-old woman, the Winona County Sheriff's Department says.

Chief Deputy Chris Cichosz told BringMeTheNews the teenager used "coercion" to rape the woman. He said it started in September and continued through January.

The victim reported the crime on Feb. 18, according to the sheriff's department.

According to Cichosz, the incidents took place at a residence in rural Winona County. He notes the woman and boy had known each other prior to the crimes, but Cichosz says he can't give any other details at this time.

The woman didn't have any physical or mental challenges, the Star Tribune reports.

Because the suspect is a minor, there are several details – such as names and locations – that are not being released yet, officials say.

The 15-year-old is being held and has been charged with third-degree criminal sexual conduct, the chief deputy is not sure yet if the boy will be charged as an adult.

In all of his years in law enforcement, Chief Deputy Cichosz tells BringMeTheNews he's never seen anything like this.

Authorities are investigating.