Eighteen students accepted the Facebook invitation to participate in the attacks at the two schools.

Six girls have been arrested in connection with a Facebook invitation to take part in what the poster called “Attack a Teacher Day” at two Nevada middle schools.

One girl was accused of inviting about 100 students on the social networking website to participate in the event on Jan. 7, and the other five were accused of responding with online threats against specific teachers, Carson Middle School Principal Dan Sadler said.

The Nevada Appeal in Carson City reported the girls were booked Jan. 5 at juvenile hall on a misdemeanor charge of communicating threats. Their names were not released.

While the students insisted it was a joke, Sadler noted they were arrested on the same day a suspended 17-year-old student in Omaha, Neb., fatally shot an assistant principal and wounded his principal before fleeing the campus and taking his own life.

“School shootings really happen. That’s why we took it seriously,” Sadler told the Associated Press on Jan. 7. Such online behavior is “not OK, and it’s not funny in this day and age if you’re going to make a threat against a teacher.”

Five of the students attend Sadler’s school, and the other attends Eagle Valley Middle School. Both schools are in Carson City.

Eighteen students accepted the Facebook invitation to participate in the attacks at the two schools, which had been set to take place from 7 a.m. to 9 a.m. on Jan. 7. A parent brought the posting to the attention of authorities, Sadler said.

Classes took place that day without incident at both schools after students earlier were notified of the arrests, and after parents of the students who were arrested or accepted the invitations were contacted by authorities.

The 12- and 13-year-old students were arrested after allegedly posting threatening statements against six teachers at the two schools. One student used the word “die” before a teacher’s name, while others wrote that they would “attack” certain teachers, Sadler said.

No specifics, such as weapons or how the attacks would be carried out, were mentioned, said Carson City sheriff’s Deputy Jessica Rivera, the school district’s resource officer. The Facebook invitation to join the attacks went out either Jan. 3 or Jan. 4.

“Even if the six girls meant it as a joke, there’s no way to know if the other students who accepted the invitation weren’t going to carry out the attacks in some fashion,” Rivera said. “The school shooting in Nebraska is just another thing that shows us you can’t take this kind of situation lightly.”