A 15-year-old Warren Central Junior High School student who told authorities she needed to protect herself because of a threat posted on Facebook was arrested Tuesday and charged with having a weapon on school grounds, Vicksburg police Lt. Bobby Stewart said.

The girl spent the night at the juvenile detention center after school officials found an 8-inch steak knife in her possession during a search just before 8 a.m. Tuesday, Stewart said this morning.

“We received a tip, and the information provided gave us reasonable suspicion to launch an investigation and a search,” Vicksburg Warren School District Superintendent Dr. Elizabeth Duran Swinford said.

Officials conducted “a very thorough search” of the backpacks, lockers and personal items of “seven to 12” female students at Vicksburg and Warren Central junior high schools. The girls were specifically named by the anonymous caller, Swinford said.

“All the kids were cleared except for one who had a knife,” she said.

As mandated in the student handbook, the girl was suspended and further disciplinary action will be considered after the district’s disciplinary review committee reviews the case, Swinford said.

She said she was not sure if the girl is a seventh- or eighth-grader, but that she is not over-age and does not have a history of trouble at school.

The girl told authorities she was afraid of trouble brewing outside school. She said she had received a threat on Facebook, an Internet-based social networking site, and felt she needed to protect herself, Stewart said.

The searched students were part of a group reported to be involved in a specific dispute outside of school, Swinford said.

“Who knows what might have happened if we had not taken the tip seriously?” she said. “She never intended to use it at school, but if I can keep blood off her hands at all, I’m glad we got involved.”

The superintendent said she brought up the issue of students bringing weapons and drugs to school at recent meetings with parents at the junior high schools.

“I told them we don’t issue guns or knives or drugs here at school, reminded them that this is a partnership and asked them please to check their children’s backpacks before school, and to be aware of what their kids are doing,” Swinford said. “I hate that we had a knife at school, but I love the fact that the parents cared and trusted us enough to call and give us the information.”

Swinford said school officials will continue checking on the reported dispute among the girls and, if warranted, will conduct more searches.

The girl was expected to be held at the detention center until her first youth court hearing, today or Thursday, Stewart said.