The Bartow, Florida, police department said that an 11-year-old girl and 12-year-old girl were discovered hiding in the bathroom of Bartow Middle School on Tuesday, armed with various knives.
Asked why she had a weapon, the girl said that she and the other student were planning on attacking as many students as possible.
Upon killing each victim, the report says, they meant to stack her or him in a bathroom stall and wait for the next small student to enter the bathroom.
School staff found the two girls, one 11-years-old and one 12-years-old, in a bathroom during class time, WJAX reported. Both girls told police they were "practicing Satanists".
Officers searched the students' phones and found that the two had discussed killing themselves after leaving their classmates' body parts by the school's entrance.
The school's assistant principal found the girls in the bathroom before they could carry out the alleged attack.
They now face charges of conspiracy to commit first-degree murder and possession of a weapon at school, among other charges.
When interviewed by officers, the girls said they wanted to kill at least 15 people. "If I had children in school I'd be half scared to death".More news: LeBron hails Ball, Stephenson after Lakers win again
They were taken to the principal's office, where one girl was found to have a butcher knife and a kitchen knife.
Hall wrote: "I understand that the recent news of a plot to kill students at Bartow Middle School is troubling".
"Killing all of these students was in hopes it would make them worse sinners ensuring that after they committed suicide ..."
The girls had a goblet in the bathroom, authorities said.
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. After one of the girl's mother received a robo-call alerting her that her child was not in second period, she called the school to inform teachers that the child should be there.
The girls remain in police custody, and a school system officials said the school will be filing for expulsion.
School staff responded quickly to reports of suspicious behavior, Superintendent Jacqueline Byrd said.
They would then cut their victims' throats, cut up their bodies, eat the flesh and drink their victims' blood.