A "small fire" was reported at Rock Hill High School on Tuesday morning, said district spokesperson Elaine Baker.
The fire was started in a student bathroom by the cafeteria. Someone set a toilet paper dispenser on fire, Baker said.
Because the dispenser itself was plastic, the fire produced a lot of "black smoke," and the "B" building, which is one of several that make up the school, was evacuated.
By 10:30 a.m., all students were back in class. The classes in the building where the fire occurred were relocated to the school's auditorium to be sure all of the smoke was cleared.
No one was hurt and there will be an investigation into the incident, Baker said.
Students at Rock Hill High took to Twitter to say the school was "on fire" and shared pictures of students in the hallway with black smoke along the ceiling. Read their tweets: