The 18-year-old sister of Charleston, S.C., church shooter Dylann Roof was arrested Wednesday for carrying pepper spray, a knife and marijuana in her high school, authorities said.

Morgan Roof also posted on Snapchat a critique of Wednesday’s National Student Walkout protest against gun violence, the Post and Courier of Charleston, S.C., reported.

“Your [sic] walking out for the allowed time of 17min, They are letting you do this, nothing is going to change what (the expletive) 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,” Roof posted, Fox 57 reported.

"I hope it’s a trap and y’all get shot." — Comment on Morgan Roof's Snapchat account

No students were harmed in connection with the arrest, Fox 57 reported.

Roof was transported to the Alvin S. Glenn Detention Center, the station reported. A $5,000 bond carried a judge’s condition that Roof not return to A.C. Flora High School, the station reported.

The school’s principal sent a letter to parents, informing them about the incident, the station reported.

Roof’s brother, Dylann Roof, was convicted on federal charges in 2016 and pleaded guilty to state charges in 2017 in connection with the June 2015 murders of nine African-American churchgoers at Emanuel AME Church in Charleston.