Morgan Roof entered AC High with marijuana, pepper spray, and a knife after posting a message on social media that police say caused panic among students.
The 18-year-old has since been arrested and charged.
No students were harmed by Roof, the sheriff’s department has reportedly said.
In a post on Snapchat, Morgan Roof said she hoped student participating in a national walkout protesting gun violence would “get shot”.
She said: “You’re walking out for the allowed time of 17min, they are letting you do this, nothing is gonna change what the f*** you think it’s gonna do?
“I hope it’s a trap and y’all get shot we know it’s not fixing nothing but black people are walking out anyway.
“No offence of course.”
In a letter to parents and students posted on Twitter, the Principal of AC High, Susan Childs, confirmed the incident.
She said: “A student used social media to post a hateful message.
“The posting was not a threat but was extremely inappropriate.
“That student was dealt with in a swift and severe manner as the posting caused quite a disruption.
“In an isolated incident, the administration was notified that there was possibly a weapon on campus.
“Through diligent work from the Assistant Principals and the School Resource Officers, an unloaded weapon was recovered.”
Dylann Roof murdered nine black parishioners in the hate-fuelled massacre on June 17 three years ago.
He later admitted to carrying out the shooting in an attempt to provoke a race war between whites and blacks in America.
The shooter was sentenced to death in January last year.
More to follow…