There is such a law in the City Code to wit:

Section 10-1-18 Weapons
A. Carrying and Discharge of Weapons Restricted
1. Except as permitted in paragraph B of this section, it is unlawful for any person within the limits of the city to fire or discharge any firearm, B-B gun, air gun, pellet gun, dart gun, slingshot, gas-operated gun or other similar gun or instrument.
2. Except as permitted in paragraph B of this section, it is unlawful for any person within the limits of the city to possess, carry or display a weapon in any public building, facility, city park or similar structure or area.
3. Except as permitted in paragraph B of this section, any person, upon entering any public place or attending a public event, may be required by the operator of the establishment or the sponsor of the event to remove his weapon and place it in the custody of the operator of the establishment or the sponsor of the event.
4. It is unlawful for any person to sell or give to a minor under the age of eighteen years, without written consent of the minor's parent or legal guardian, a weapon, ammunition or toy pistol by which dangerous and explosive substances may be discharged.

B. Exceptions
1. Paragraph A(1) of this section shall not apply in the following circumstances:
(a) As allowed pursuant to the provisions of Title 13, Chapter 4 of the Arizona
Revised Statutes;
(b) On a properly supervised range;
(c) By special permit of the city or chief of police of the city for the use of such
gun or instrument for a valid and proper purpose, and for use in a manner not
likely to harm any person, animal or property;
(d) For hunting or animal control purposes on property designated as Special
Rural by the city council as specially designated for exemption from this
subsection or other sections of this Chapter 10; provided that all such activity
complies in all respects with all other rules, regulations, or requirements set forth
by this code, Arizona State Statute, Federal Law, Agencies of the Federal
Government, the Arizona Department of Game and Fish or other entity having
authority or control.
2. The provisions of paragraphs A(2) and A(3) of this section shall not apply to a duly licensed peace officer or any person summoned by any peace officer to
assist and while actually assisting in the performance of official duties.