PAWNEE, Oklahoma - An 18-year-old Pawnee High School student is behind bars, accused of threatening the high school principal. The Pawnee County Sheriff's Office said that student told a friend that he was going to bring a pistol to school to kill the principal.

"Honestly, the first thing that I said was 'are you serious?,'" said Pawnee High School Principal Stacy Womack.

That's the first thought that ran through Womack's head after the Pawnee County Sheriff's Office said a student threatened to shoot her.

"The student and I had a conversation yesterday. It was a simple conversation. I would've never thought that something like this would've come from this specific student," said Womack.

Superintendent Ned Williams said the district has a zero tolerance policy when it comes to threats or harassment. He said a bus driver overheard a student making the threat Tuesday afternoon and reported it.

"Pulled cameras from the bus and identified the student. It was a student that had enrolled in Pawnee this fall - transferred here from a neighboring school district," said Williams.

Eighteen-year-old Dalton Mitchell, a high school senior, was identified as the suspect. Mitchell was arrested after the the Sheriff's Office interviewed him and the driver.

Williams said the student also threatened a teacher. He said the school notified employees, parents and students. Parent Don Brown said he doesn't understand why someone would make a threat like that.

"It does frustrate me as a parent and a grandparent. I've got a grandson and granddaughter that's going up here to this school," said Brown.

Meanwhile Williams and Womack both said they want parents and students to know: "When they come to school I want them to know that we are going to do everything that is within our power to protect their kids," said Womack.

Mitchell was arrested on a complaint of threatening to perform violent acts.