Minimum number of officials for a game

[CaUmpJW]

What is the minimum number of officials your association requires to start a varsity high school game. Our officials travel great distances at times to get to a game. We assign five officials per game. Sometimes an official is late or does not make it for a number of various reasons. We would do the game with four officials. Our number one concern is safety of the players. Would your association start a game with three officials? We are looking for guidelines and what other associations do?