(TAMPA, Fla.) — A pair of 14-year-old Florida middle school girls are facing felony charges for conspiracy to commit kidnapping and murder after being arrested this week in what authorities described as a plot to kidnap and kill 9 people.Court records reviewed by ABC News Tampa affiliate WFTS indicate that a teacher told police she observed the girls acting “hysterical” while searching for a folder at school, and heard one say that “I’m just going to tell them it’s a prank if they call me or if they find it.” ABC News is withholding the identity of the girls due to their age.The teacher located the folder, which allegedly contained eight handwritten notes detailing the kidnapping and murder plot, and notified authorities, according to WFTS. The letters outlined plans to obtain guns and discussed the transportation and disposal of bodies. One contained plans about what the two youngsters would wear during the kidnappings and murders.The folder was labeled “Private info,” “Do not open” and “Project 11/9,” according to the TV station.The teenagers were taken into custody and each face nine counts of criminal attempt to conspire capital felony (premeditated homicide), and three counts of criminal attempt to conspire third-degree felony (kidnapping), WFTS reported.Officials said they are treating the plot seriously.”It doesn’t matter if they thought it was a joke,” Highlands County Sheriff’s Office (HCSO) spokesman Scott Dressel told WFTS. “It’s not a joke. There’s no joking about something like this. You don’t make a joke about killing people. It’s not a joke.”Highlands County Schools Deputy Superintendent Andrew Lethbridge said in a statement to WFTS that the school’s safety protocols were effective.“We would like to remind students (and everyone) that we are all held accountable for the information that we communicate,” he said in the statement.“The [district] takes threats very seriously and we work closely with the HCSO to investigate them. We have stressed the concept that if staff or students hear or see something that concerns them, to please share that information with someone that can do something about it. In this situation, we witnessed this concept in action. This enables us to be proactive and respond to situations prior to an incident taking place.” Copyright © 2019, ABC Radio. All rights reserved.