A quiet afternoon in Tonkawa, Oklahoma turned into a nightmare when police announced they stopped a teenage girl with a plan to kill her classmates.

Officers discovered a "hit list" and research about serial killers in the 13 year old's journal after searching her home, and said she allegedly planned to open fire at her school with her family's guns.

Students and parents from Tonkawa High School told KFOR that the incident left them totally shocked.

"You don't think something like that's going to happen in Tonkawa," student Kaitlyn Jordan told KFOR.

The unsettling plot unraveled Sunday when someone called police with a disturbing tip, which led officers to the 13 year old.

"It's not your typical actor in this kind of event, this type of incident," Cpl. Nick Payne told KFOR.

Investigators sat the child down for an interview after searching her house.

"When I was speaking with her, that was the first thing I noticed, she was very intelligent," Payne told KFOR.

Officers said she had multiple scenarios planned to hurt her peers.

After she was arrested, police contacted everyone on her hit list to say she was in custody.

"They were pretty shocked. It's kind of a hard thing to take, to hear something like that," Payne told KFOR.

Since officials believe the girl planned to act alone, school resumed as usual -- but that hasn't stopped residents from wondering what could have motivated her.

"I don't know if she was being bullied or what was happening in her life," Jordan told KFOR.

The 13 year old has been charged with felony threats to perform acts of violence, and is being held in a juvenile detention center.

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