Cal. Elec. Code § 14401

When the polls are closed, the precinct board shall proclaim that fact aloud at the place of election. After the proclamation no ballot shall be received. However, if at the hour of closing there are any other voters in the polling place, or in line at the door, who are qualified to vote and have not been able to do so since appearing, the polls shall be kept open a sufficient time to enable them to vote.