(a) A municipality or county to which this chapter applies and that employs or supervises first responders may not adopt or enforce an ordinance, order, or other measure that generally prohibits a first responder who holds a license to carry a handgun under Subchapter H, Chapter 411, Government Code, an unexpired certificate of completion from the department under Section 411.1883(d), Government Code, and the required liability policy under Section 179.053 from:
(1) carrying a concealed or holstered handgun while on duty; or
(2) storing a handgun on the premises of or in a vehicle owned or leased by the municipality or county if the handgun is secured with a device approved by the department under Section 411.1883(f), Government Code.
(b) This section does not prohibit a municipality or county from adopting an ordinance, order, or other measure that:
(1) prohibits a first responder from carrying a handgun while on duty based on the conduct of the first responder; or
(2) limits the carrying of a handgun only to the extent necessary to ensure that carrying the handgun does not interfere with the first responder's duties.