(1) A person, owner, or motor carrier shall not drive a bus or cause or permit a bus to be driven or moved, unless the bus is equipped with properly filled fire extinguishers as follows:

  (a) If the bus is used to transport hazardous materials and required to be marked or placarded pursuant to 49 C.F.R. § parts 100 to 199, a fire extinguisher having an underwriters laboratories rating of 10 B:C or more.

  (b) If the bus is not used to transport hazardous materials, either a fire extinguisher having an underwriters laboratories rating of 5 B:C or more, or 2 fire extinguishers having an underwriters laboratories rating of 4 B:C or more.

  (2) The fire extinguishers required by this section shall be securely mounted on the vehicle in a location readily accessible for use. The fire extinguishers shall be designed, constructed, and maintained to permit a determination of whether they are fully charged and in proper operating condition.

  (3) A fire extinguisher, required under this section, must have an extinguishing agent that does not need protection from freezing.

  (4) A fire extinguisher, required under this section, must not use a vaporizing liquid that gives off vapors more toxic than those shown as having toxicity rating of 5 or 6 in the underwriters’ laboratories classification of comparative life hazard of gases and vapors.

  (5) Each fire extinguisher required under this section must be labeled or marked with its underwriters’ laboratories rating.