(CNN) The sister of Charleston church shooter Dylann Roof was arrested Wednesday on charges of bringing weapons and drugs to her South Carolina high school, authorities said.

Morgan Roof, 18, was arrested after a school resource officer at the A.C. Flora High School in Columbia, South Carolina was notified that Roof was carrying marijuana, pepper spray and a knife on campus, the Richland County Sheriff's Department said.

Roof had also made an alarming Snapchat post expressing anger about the National School Walkout, The Post and Courier reported. A 17-minute walkout was staged at schools around the country on Wednesday to honor the 17 people killed at Florida's Marjory Stoneman Douglas High School last month and call for stricter gun control laws .

No A.C. Flora High students were harmed Wednesday, authorities said.

Roof was charged with simple possession of marijuana and two counts of carrying weapons on school grounds. A judge set a $5,000 bond for Roof under the condition that she would not return to the school, CNN affiliate WIS reported.

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