The sister of Dylann Roof, the man who shot and killed nine people at a Charleston, South Carolina, church in 2015, was arrested Wednesday after authorities said she brought weapons and drugs to school.

According to WIS-TV, Morgan Roof, 18, is accused of bringing a knife, pepper spray and marijuana to A.C. Flora High School in Forest Acres. She was arrested on charges of carrying weapons on school property and simple possession of marijuana, the station reported.

Authorities also said one of Morgan Roof's social media posts about the National School Walkout, a protest against gun violence in schools, worried other students.

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"Your [sic] walking out for the allowed time of 17min, they are letting you do this, nothing is gonna change what tf you think it's gonna do?" she posted on Snapchat, according to WACH. "I hope it's a trap and y'all get shot we know it's fixing to be nothing but black people walkin [sic] out anyway."

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Morgan Roof's bond reportedly was set at $5,000.

WATCH: Scenes from National School Walkout