Cal. Gov. Code § 54957.9

In the event that any meeting is willfully interrupted by a group or groups of persons so as to render the orderly conduct of the meeting unfeasible and order cannot be restored by the removal of individuals who are willfully interrupting the meeting, the members of the legislative body conducting the meeting may order the meeting room cleared and continue in session. Only matters appearing on the agenda may be considered in such a session. Representatives of the press or other news media, except those participating in the disturbance, shall be allowed to attend any session held pursuant to this section. Nothing in this section shall prohibit the legislative body from establishing a procedure for readmitting an individual or individuals not responsible for willfully disturbing the orderly conduct of the meeting.