(5) Emergency detention of juvenile. If the juvenile is believed to have a mental illness or developmental disability or to be drug dependent and exhibits conduct that constitutes a substantial probability of physical harm to the juvenile or to others, or a very substantial probability of physical impairment or injury to the juvenile exists due to the impaired judgment of the juvenile and if the standards of s. 51.15 are met, the person taking the juvenile into physical custody, the intake worker, or other appropriate person shall proceed under s. 51.15.