Female school shooters are far more rare than their male counterparts, but not unheard of. (File)

Alexis Wilson was working an afternoon shift at the local Pizza Inn in McAlester, Oklahoma, on Sunday, when she pulled a co-worker aside to boast about her new gun.

The slight 18-year-old with large brown eyes clutched her iPhone and pressed play on a video of her shooting a newly purchased AK-47, according to an incident report. Then Wilson told the other teenage waitress how much she resented the people at her old school - allegedly adding that she wanted to "shoot 400 people for fun."

The chilling conversation shook Wilson's co-worker. She reported it to a manager, who called the McAlester police.

On Monday, the Pittsburg County Sheriff's Office said Wilson was charged with a felony for making a terrorist threat against McAlester High School.

"In today's times, you can't say stuff like that," Pittsburg County Sheriff Chris Morris told KTUL. "We're going to take it serious and investigate it to the fullest extent and make an arrest if possible because we do not want any of our schools getting shot up - nobody does."

Wilson has pleaded not guilty. Her lawyer did not immediately return a request for comment.

The 5-foot-7, baby-faced teenager is an anomaly as a female suspect allegedly plotting a mass shooting, but police described her as a serious threat.

The high school she allegedly targeted had suspended her once for bringing a knife to school and again for displaying swastikas on her personal belongings, a school resource officer told the sheriff's office. Her booking photo shows Wilson wearing a T-shirt referencing "The Anarchist Cookbook," a 1971 book advocating for violent civil disobedience that has been found among the belongings of school shooters. On Facebook, Wilson had liked a documentary about the 1999 Columbine High School massacre.

"A female can pull the trigger just as easily as a male," Morris told KTUL Monday. "It's rare, it's different. I don't know that there's been a female accused of this."

Female school shooters are far more rare than their male counterparts, but not unheard of. One of the most well-known was 16-year-old Brenda Spencer, who opened fire on an elementary school in 1979 through the window of her home, killing two adults and injuring eight children and one police officer. Spencer became infamous for the motive she offered a reporter who phoned her during the attack. "I don't like Mondays," she reportedly said. "This livens up the day."

After Wilson's shift at the pizza shop ended on Monday, Sergeant Micah Stites and Deputy Matthew Jordan knocked on Wilson's front door. Wilson agreed to talk, police said.

She denied showing her co-worker a video of her shooting the AK-47, but admitted she had talked about the gun and had showed off photos of her posing with it. She played videos of her shooting the rifle for Stites and Jordan, police said. During the interview, Wilson appeared nervous to the sheriff's officers. Her voice shook and she jumped from topic to topic mid-sentence, they said.

The young woman told Jordan she had "disturbing and criminal-like things" on the phone. She said she was bullied at McAlester High School.

After she had been suspended in her freshman year, she said, she completed a program at Thunderbird, a military academy in Oklahoma that advertises itself as an alternative option to public school. She said she tried to re-enroll at McAlester High afterward, but she hadn't been allowed to start classes this fall. Wilson explained the alleged threat by saying she had been trying to convince her co-worker that "not everyone that owns a gun is a bad person," the police report said.

"She said that she would never shoot up a school or people," Jordan wrote in his report, "and that her co-worker must have taken what she said wrong."

Stites and Jordan collected an iPhone with a purple case, an AK-47 with six magazines and a 12-gauge shotgun with a stock sleeve for extra shells from Wilson's bedroom.

At the end of the police interview, Wilson told the officers that she used to feel "suicidal and borderline homicidal" toward her classmates at McAlester High because of the bullying she faced. Jordan asked her if she thought about hurting anyone at the school.

"Not recently, but she has in the past," the report says.

Wilson's mother, Sonya Smith, said her daughter is innocent at Monday afternoon's arraignment hearing, the McAlester News-Capital reported. She told sheriff's deputies that she knew about her daughter's guns, but "didn't think anything of it" because Wilson had long been a marksman and hunter.

The school district's superintendent, Randy Hughes, said that McAlester High would be open on Tuesday.

"We're living in scary times when we have to worry about the safety of our children in school," Hughes said in a statement.