Cal. Health & Safety Code § 12090

There shall not be included in any cargo of explosives any flammable or combustible liquids, acids, or corrosive liquids, oxidizers, or combustible materials, other than the explosives themselves, which may have such characteristics. Blasting caps or detonators shall not be transported upon the same vehicle with other explosives. The foregoing provisions of this section shall be subject to such exceptions as are permitted by the regulations of the United States Department of Transportation.