It shall be a crime for any person under the age of twenty-one to carry or otherwise have in his or her possession any firearm within the limits of the city of New York, unless such person has a valid permit or license or is otherwise exempted by law. If a partnership or corporation carries or has in its possession a firearm, no member, officer or employee of such partnership or corporation under the age of twenty-one shall carry or have in his or her possession such firearm within the limits of the city of New York.