Transcript for Church shooter's sister arrested after social media post
We turn now to the school scare in the same community in South Carolina that witnessed that deadly church shooting. You'll remember when dylann roof went into the church and killed so many. Tonight, his sister, Morgan roof, has been arrested for allegedly bringing a knife and pepper spray and drugs to school. Her brother is not on death row for killing nine people at that church. Morgan roof also accused of posting disturbing messages online. Here's ABC's Steve osunsami. Reporter: This was happening as students across the country were walking out of school, protesting gun violence. School administrators at ac flora high school in Columbia, South Carolina, were racing to find 18-year-old Morgan roof. She had just shared this message on social media that was read by other students, saying that she hoped the walkout was "A trap" and that students "Get shot." "We know it's fixing to be nothing but black people walking out anyway." When they found her, police say she was carrying marijuana, pepper spray and a knife. She was arrested, and even the governor is saying that a "Potential tragedy was avoided" at the high school. The teenagers comments about black people strike a nerve, because she's the younger sister of this young man. Dylann roof, who is seen here entering a black church in Charleston, where he killed nine people in 2015, and spoke proudly about wanting to start a race war. Well, I don't like what black people do. Reporter: Dylann roof tonight is on death row in Indiana. His sister, who has not yet entered a plea, is out on bond. David? Steve, thank you.
This transcript has been automatically generated and may not be 100% accurate.