(c) A school marshal appointed by the board of trustees of a school district or the governing body of an open-enrollment charter school may carry a concealed handgun or possess a handgun on the physical premises of a school, but only:
(1) in the manner provided by written regulations adopted by the board of trustees or the governing body; and
(2) at a specific school as specified by the board of trustees or governing body, as applicable.
(d) Any written regulations adopted for purposes of Subsection (c) must provide that a school marshal may carry a concealed handgun on the school marshal's person oras described by Subsection (c), except that if the primary duty of the school marshal involves regular, direct contact with students, the marshal may not carry a concealed handgun but may possess thea handgun on the physical premises of a school in a locked and secured safe or other locked and secured locationwithin the marshal's immediate reach when conducting the marshal's primary duty. The written regulations must also require that a handgun carried or possessed by or within access of a school marshal may be loaded only with frangible duty ammunition approved for that purpose by the Texas Commission on Law Enforcement.