The younger sister of Dylan Roof, who was sentenced to death for murdering nine black churchgoers in Charleston, South Carolina, was arrested Wednesday, ABC News reports.

Morgan Roof, 18, was arrested at A.C. Flora High School in Columbia, South Carolina after school officials told police that she had a knife, pepper spray, and marijuana in her possession. She is also accused of posting an alarming message on social media.

"Your walking out of the allowed time of 17min, they are letting you do this, nothing is gonna change what tf you think it's gonna do? I hope it's a trap and y'all get shot we know it's fixing to be nothing but black people walkin out anyway," the post said, according to several media outlets.

Authorities say she was charged with one count of marijuana possession and two counts of carrying a weapon on school grounds.