Cal. Welfare and Institutions Code § 305

Any peace officer may, without a warrant, take into temporary custody a minor: (a) When the officer has reasonable cause for believing that the minor is a person described in Section 300, and, in addition, that the minor has an immediate need for medical care, or the minor is in immediate danger of physical or sexual abuse, or the physical environment or the fact that the child is left unattended poses an immediate threat to the child’s health or safety. In cases in which the child is left unattended, the peace officer shall first attempt to contact the child’s parent or guardian to determine if the parent or guardian is able to assume custody of the child. If the parent or guardian cannot be contacted, the peace officer shall notify a social worker in the county welfare department to assume custody of the child. (b) Who is in a hospital and release of the minor to a parent poses an immediate danger to the child’s health or safety. (c) Who is a dependent child of the juvenile court, or concerning whom an order has been made under Section 319, when the officer has reasonable cause for believing that the minor has violated an order of the juvenile court or has left any placement ordered by the juvenile court. (d) Who is found in any street or public place suffering from any sickness or injury which requires care, medical treatment, hospitalization, or other remedial care.