Greenville, S.C. - Four students with the Greenville County School District (GCSD) have been charged, school administrators said Wednesday, for allegedly making threats against the district.

The charges originate from four separate incidents within four separate schools, according to Superintendent of Schools Burke Royster.

The four incidents were investigated by the Greenville County Sheriff's Office. Royster says all four students charged have also been recommended for expulsion.

This comes just a day after the district sent a letter out to parents, asking them to closely monitor their children's social media activity, in light of the Sept. 4 school shooting in Winder, Ga., in which four people were killed, including two high school students.