It is a felony under South Carolina law for anyone except state, county or municipal law-enforcement officers or personnel authorized by school officials to carry, while on school property: a knife, blackjack, metal pipe or pole, firearm or any other type of weapon or device that may be used to inflict bodily injury.

If charged as an adult of this crime and convicted, a person could face up to 5 years in prison and up to $1,000 in fines.  S.C. Code Section 16-23-430. 

Also, if a juvenile brings a firearm onto school property, he or she must be expelled from school for at least one year.  S.C. Code Section 59-63-235.