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DAVIE (CBSMiami) – An 11-year-old girl is under arrest Thursday for writing a note threatening to kill and sliding the note under the door of her Assistant Principal at Nova Middle School.

According to Davie Police, the 6th grader is charged with one count of written threats to kill or do bodily injury which is a felony.

The note, released by police, reads, “I will bring a gun to school to kill all of you ugly ass kids and teachers bitch. I will bring the gun Feb, 16, 18. BE prepared bitch!”

Police say surveillance video also shows the student placing the note under the door. The video has not been released.

In a handwritten confession, also released by police, she wrote, “”I placed a note under the AP door and I got caught on tape. My friend Sarai to write the letter or she will get her friend to fight me because she does not like because someone said that I like (name withheld). So to avoid getting into a fight with her friend I put the letter under the door.”

The girl was taken into custody and transported to the Broward Juvenile Assessment Center.

“This arrest is evident that these types of crimes will be taken serious,” wrote Davie Police Sgt. Mark Leone.

Since Wednesday’s massacre at Marjory Stoneman Douglas High School, “copycat” threats were made at other schools, Broward Sheriff Scott Israel said at a news conference Thursday.

“We will respond to every threat. Every threat we receive, we will not classify it as a copycat or prank call,” Israel said. “We will respond in full and investigate it.”

But “any call that is made fictitiously, any fake call, any call that is made to take out resources at a time like this and place them in places where we don’t need to be, we will do the full power of the sheriff’s office. We’ll investigate this and charge anyone accordingly with the maximum charge we possibly could for doing something so horrific, so pathetic.”

One false alarm at a nearby school Thursday morning was unfounded, the sheriff’s office said, but while at the school, “a deputy accidentally discharged his gun and injured his leg.”