California Code, Penal Code - PEN § 422.3

(a) Except as provided in subdivision (b), any person who willfully threatens, by any means, including, but not limited to, an image or threat posted or published on an internet web page, to commit a crime that will result in death or great bodily injury to another person or persons at a daycare, school, university, workplace, house of worship, or medical facility with specific intent that the statement is to be taken as a threat, even if there is no intent of actually carrying it out, if the threat on its face and under the circumstances in which it is made is so unequivocal, unconditional, immediate, and specific as to convey to the person or persons threatened a gravity of purpose and an immediate prospect of execution of the threat, and if that threat causes a person or persons to reasonably be in sustained fear for their own safety or the safety of others at these locations, shall be punished by imprisonment in the county jail not to exceed one year or by imprisonment pursuant to subdivision (h) of Section 1170.

(b) If a person who commits an act in violation of subdivision (a) is under 18 years of age, the person shall be referred to services pursuant to Section 654 of the Welfare and Institutions Code, if eligible.  If ineligible, the offense shall be punished as a misdemeanor.

(c) This section does not preclude or prohibit prosecution under any other law, except that a person shall not be convicted for the same threat under both this section and Section 422.