Two Florida girls brought knives to their middle school in an alleged attempt to kill and mutilate fellow students for satanic reasons, officials said Wednesday.

No one was harmed in the foiled plot, which was discovered Tuesday at Bartow Middle School in central Florida, school officials said.

Police say the girls — ages 11 and 12 — were found in a bathroom stall, allegedly with multiple knives, a pizza cutter and knife sharpener in their possession. The girls planned to commit suicide after stabbing other students, police say.

"The plan was to kill at least 1 student but were hoping to kill anywhere from 15-25 students," an affidavit said. "Killing all of these students was in hopes it would make them worse sinners ensuring that after they committed suicide ... (they) would go to hell so they could be with satan."

The girls allegedly hatched the plot after watching scary movies over the weekend, detectives said. The plan involved lying in wait for smaller students, mutilating their victims' bodies and drinking their victims' blood, according to authorities.

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After the girls were arrested, investigators found messages on their phones about the plotted attack, WTVT reports. One such message read, "We will leave body parts at the entrance and then we will kill ourselves," the station reports, citing police.

Bartow Chief of Police Joe Hall called the plot "horrific" in a statement posted to social media by Polk County Public Schools. Hall went on to say that officials' safety plan helped prevent the alleged attack from occurring.

That plan was triggered as administrators searched for the students after they didn't show up for class Tuesday.

Prosecutors will determine whether the girls will be charged as juveniles or adults, Deputy Police Chief Bryan Dorman told the Associated Press in an email. Among the charges they face: conspiracy to commit first-degree murder and possession of a weapon at school. The girls were sent to a juvenile detention facility.

Contributing: The Associated Press.