1. After a petition has been filed, unless the parties appear voluntarily, the juvenile court shall issue a summons in the name of the state of Missouri requiring the person who has custody of the child to appear personally and, unless the court orders otherwise, to bring the child before the court, at the time and place stated.
2. If the person so summoned is other than a parent or guardian of the child, then the parent or guardian or both shall also be notified of the pendency of the case and of the time and place appointed.
3. If it appears that the child is in such condition or surroundings that his or her welfare requires that his or her custody be immediately assumed by the court, the judge may order, by endorsement upon the summons, the officer serving it to take the child into custody at once.
4. Subpoena may be issued requiring the appearance of any other person whose presence, in the opinion of the judge, is necessary.