571.030 - Unlawful use of weapons--exceptions--penalties.
1. A person commits the crime of unlawful use of weapons if he or she knowingly:
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
4. Subdivisions (1), (8), and (10)
of subsection 1 of this section shall not apply to any person who has a valid concealed carry endorsement
issued pursuant to sections 571.101 to 571.121 or a valid permit or endorsement to carry concealed firearms issued by another state or political subdivision of another state.
5. Subdivisions (3), (4), (5), (6), (7), (8), (9), and (10)
of subsection 1 of this section shall not apply to persons who are engaged in a lawful act of defense pursuant
to section 563.031.
571.107. - Endorsement does not authorize concealed firearms, where--penalty for violation.
1. A concealed carry endorsement issued pursuant to sections 571.101 to 571.121.....
(10) Any higher education institution or elementary or secondary school facility without the consent of the governing body of the higher education institution or a school official or the district school board
. Possession of a firearm in a vehicle on the premises of any higher education institution or elementary or secondary school facility shall not be a criminal offense so long as the firearm is not removed from the vehicle or brandished while the vehicle is on the premises;
563.031 - Use of force in defense of persons. http://www.moga.mo.gov/statutes/C500-599/5630000031.HTM