San Luis Obispo Police identified the person responsible for writing the threatening message on the girl's bathroom mirror on Monday.
Police, along with Laguna Middle School administration, say a 13-year-old female student at the school is believed to have written the message "School Shooting 12-02-19."
They believe the student did this with the knowledge and encouragement of two of her friends.
Due to the ages of the students their names are not being released.
San Luis Obispo Police believe the message was written to support a trend currently being encouraged on TikTok, a popular social media app.
They say numerous TikTok videos have been circulating during the last several weeks urging teens to skip school on December 2nd, 2019.
The student who wrote this message was believed to have been following this trend and used the writing as a means to get other students to skip school on December 2nd.
Police do not believe the students had any intent to threaten anyone, or to follow through with a shooting or any other acts of violence.
Police notified the student's parents and informed them about the serious nature of this incident.
After further investigation, police did not make any arrests and all the students involved will be dealt with administratively through the school district.
Police and school officials feel confident this matter was dealt with aggressively and swiftly, and there is no ongoing threat towards Laguna Middle School students, staff or their families.