Updated

A sex education book full of illustrations depicting sexual acts has ignited a controversy after it was left at an Oregon elementary school library, according to a report late Thursday.

The principal at Hudson Park Elementary School in Rainier admitted in a letter to parents Thursday that the book was inappropriately shown to fourth-graders in the library recently, Fox 12 Oregon reported. Angry parents were told the book had been pulled from shelves.

The book in question, “It’s Perfectly Normal,” explains bodies, sex and sexual health, the station reported.

The illustrations in the book include pages of naked teens and adults, some depicting sex acts and even masturbation, the station reported.

Rainier School District officials defended “It’s Perfectly Normal,” according to Fox 12. The officials said the book has been approved for students 10 and up and is on the state-approved list of books allowed at the school.

The school district told the station a sixth grade class accidentally left the books out where a fourth grade class found and read them.

School officials said it was an honest mistake.

But parents of some of those 4th graders who spoke to Fox 12 accused the school librarian of showing them to their children, even encouraging them to take the book home.

The parents said some 4th graders who saw the book are only 9.

The letter to parents from the principal included an apology, the station reported.

“Inappropriate human development and sexuality books were disseminated to students who had library,” the letter also said, according to the station. “Procedures have been put in place to make sure this doesn’t happen again.”

District officials also told the station the librarian had been “disciplined.”

Click here for more from Fox 12 Oregon.