U.S. Code : Title 18 : Section 922
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(2)(A) It shall be unlawful for any individual knowingly to
possess a firearm that has moved in or that otherwise affects
interstate or foreign commerce at a place that the individual
knows, or has reasonable cause to believe, is a school zone.
(B) Subparagraph (A) does not apply to the possession of a
firearm -
(i) on private property not part of school grounds;
(ii) if the individual possessing the firearm is licensed to do
so by the State in which the school zone is located or a
political subdivision of the State, and the law of the State or
political subdivision requires that, before an individual obtains
such a license, the law enforcement authorities of the State or
political subdivision verify that the individual is qualified
under law to receive the license;
(iii) that is -
(I) not loaded; and
(II) in a locked container, or a locked firearms rack that is
on a motor vehicle;
(iv) by an individual for use in a program approved by a school
in the school zone;
(v) by an individual in accordance with a contract entered into
between a school in the school zone and the individual or an
employer of the individual;
(vi) by a law enforcement officer acting in his or her official
capacity; or
(vii) that is unloaded and is possessed by an individual while
traversing school premises for the purpose of gaining access to
public or private lands open to hunting, if the entry on school
premises is authorized by school authorities.
(3)(A) Except as provided in subparagraph (B), it shall be
unlawful for any person, knowingly or with reckless disregard for
the safety of another, to discharge or attempt to discharge a
firearm that has moved in or that otherwise affects interstate or
foreign commerce at a place that the person knows is a school zone.
(B) Subparagraph (A) does not apply to the discharge of a firearm
-
(i) on private property not part of school grounds;
(ii) as part of a program approved by a school in the school
zone, by an individual who is participating in the program;
(iii) by an individual in accordance with a contract entered
into between a school in a school zone and the individual or an
employer of the individual; or
(iv) by a law enforcement officer acting in his or her official
capacity.
(4) Nothing in this subsection shall be construed as preempting
or preventing a State or local government from enacting a statute
establishing gun free school zones as provided in this subsection.
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full text can be found
here
hope that helps.