Unlawful use of weapons--exceptions--penalties.
RSMo 571.030. 1. A person commits the offense of unlawful use of weapons, except as otherwise provided by sections 571.101 to 571.121, if he or she knowingly:
(10) Carries a firearm, whether loaded or unloaded, or any other weapon readily capable of lethal use into any school, onto any school bus, or onto the premises of any function or activity sponsored or sanctioned by school officials or the district school board; or
3. Subdivisions (1), (5), (8), and (10) of subsection 1 of this section do not apply when ... Subdivision (10) of subsection 1 of this section does not apply if the firearm is otherwise lawfully possessed by a person while traversing school premises for the purposes of transporting a student to or from school, or possessed by an adult for the purposes of facilitation of a school-sanctioned firearm-related event or club event.
4. Subdivisions (1), (8), and (10) of subsection 1 of this section shall not apply to any person who has a valid concealed carry permit issued pursuant to sections 571.101 to 571.121, a valid concealed carry endorsement issued before August 28, 2013, or a valid permit or endorsement to carry concealed firearms issued by another state or political subdivision of another state.
7. Nothing in this section shall make it unlawful for a student to actually participate in school-sanctioned gun safety courses, student military or ROTC courses, or other school-sponsored or club-sponsored firearm-related events, provided the student does not carry a firearm or other weapon readily capable of lethal use into any school, onto any school bus, or onto the premises of any other function or activity sponsored or sanctioned by school officials or the district school board.