No person shall, without a permit, park any motor vehicle in a preferential parking district in violation of any parking restrictions set forth herein or in a resolution establishing a preferential parking district, except for the following:
(a) Repair, maintenance, refuse, utility, fuel or delivery vehicles doing business in the district.
(b) Vehicles delivering life support and health commodities to residential areas or schools located in the preferential parking district.
(c) Police vehicles and other public safety or emergency vehicles operated by or under the authority of a governmental entity while engaged in the performance of official duties.
(d) Any other vehicle expressly authorized by law to park within the district, notwithstanding the provisions of this chapter.