A pupil shall not be suspended from school or recommended for expulsion, unless the superintendent of the school district or the principal of the school in which the pupil is enrolled determines that the pupil has committed an act as defined pursuant to any of subdivisions (a) to (r), inclusive: (a)

• (1) Caused, attempted to cause, or threatened to cause physical injury to another person.
• (2) Willfully used force or violence upon the person of another, except in self-defense. (b) Possessed, sold, or otherwise furnished a firearm, knife, explosive, or other dangerous object, unless, in the case of possession of an object of this type, the pupil had obtained written permission to possess the item from a certificated school employee, which is concurred in by the principal or the designee of the principal.

(c) Notwithstanding subdivision (b), the principal of a school or the principal’s designee shall notify the appropriate law enforcement authorities of the county or city in which the school is located of any acts of a pupil that may involve the possession or sale of narcotics or of a controlled substance or a violation of Section 626.9 or 626.10 of the Penal Code. The principal of a school or the principal’s designee shall report any act specified in paragraph (1) or (5) of subdivision (c) of Section 48915 committed by a pupil or nonpupil on a schoolsite to the city police or county sheriff with jurisdiction over the school and the school security department or the school police department, as applicable.

(c) The principal or superintendent of schools shall immediately suspend, pursuant to Section 48911, and shall recommend expulsion of a pupil that he or she determines has committed any of the following acts at school or at a school activity off school grounds:

• (1) Possessing, selling, or otherwise furnishing a firearm. This subdivision does not apply to an act of possessing a firearm if the pupil had obtained prior written permission to possess the firearm from a certificated school employee, which is concurred in by the principal or the designee of the principal. This subdivision applies to an act of possessing a firearm only if the possession is verified by an employee of a school district. The act of possessing an imitation firearm, as defined in subdivision (m) of Section 48900, is not an offense for which suspension or expulsion is mandatory pursuant to this subdivision and subdivision (d), but it is an offense for which suspension, or expulsion pursuant to subdivision (e), may be imposed. [...] (f)  The governing board of a school district shall refer a pupil who has been expelled pursuant to subdivision (b) or (e) to a program of study that meets all of the conditions specified in subdivision (d). Notwithstanding this subdivision, with respect to a pupil expelled pursuant to subdivision (e), if the county superintendent of schools certifies that an alternative program of study is not available at a site away from a comprehensive middle, junior, or senior high school, or an elementary school, and that the only option for placement is at another comprehensive middle, junior, or senior high school, or another elementary school, the pupil may be referred to a program of study that is provided at a comprehensive middle, junior, or senior high school, or at an elementary school. (g)  As used in this section, “knife” means any dirk, dagger, or other weapon with a fixed, sharpened blade fitted primarily for stabbing, a weapon with a blade fitted primarily for stabbing, a weapon with a blade longer than 3½ inches, a folding knife with a blade that locks into place, or a razor with an unguarded blade. (h)  As used in this section, the term “explosive” means “destructive device” as described in Section 921 of Title 18 of the United States Code.