California Code, Welfare and Institutions Code - WIC § 5585.50

(a) When any minor, as a result of mental disorder, is a danger to others, or to himself or herself, or gravely disabled and authorization for voluntary treatment is not available, a peace officer, member of the attending staff, as defined by regulation, of an evaluation facility designated by the county, or other professional person designated by the county may, upon probable cause, take, or cause to be taken, the minor into custody and place him or her in a facility designated by the county and approved by the State Department of Health Care Services as a facility for 72-hour treatment and evaluation of minors. The facility shall make every effort to notify the minor's parent or legal guardian as soon as possible after the minor is detained.

(b) The facility shall require an application in writing stating the circumstances under which the minor's condition was called to the attention of the officer, member of the attending staff, or professional person, and stating that the officer, member of the attending staff, or professional person has probable cause to believe that the minor is, as a result of mental disorder, a danger to others, or to himself or herself, or gravely disabled and authorization for voluntary treatment is not available. If the probable cause is based on the statement of a person other than the officer, member of the attending staff, or professional person, the person shall be liable in a civil action for intentionally giving a statement which he or she knows to be false.