(CNN) A rural Oklahoma school system closed for two days earlier this week after a group of adults made threatening Facebook comments about a 12-year-old transgender girl, Achille Public Schools Superintendent Rick Beene said.

The incident began after the student used the middle school girl's bathroom this year at Achille school system in southern Oklahoma, Beene said. In previous years at the district elementary school, she had used the staff bathroom.

Two district parents complained about her use of the girl's bathroom in a private Facebook group called "Achille ISD Parents Group," which is not officially affiliated with the school, according to Beene.

The threats escalated in severity and number when someone made the Facebook group public, Beene said, and some of the Facebook threats have been traced to other parts of Oklahoma and Texas.

According to CNN affiliate KXII , Facebook commenters called the seventh grader, "it" and "thing." One Facebook poster suggested it was open hunting season for transgender people, and others advocated for the 12-year-old to be stabbed or beaten up.

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