If a county board of supervisors or a city council has appointed itself as the district board, the board of supervisors or city council may delegate any or all of its powers to a fire commission composed of five or seven commissioners. In the case of a district governed by a board of supervisors, the commissioners may be councilmembers of cities which are located in the district. The board of supervisors or city council shall determine whether the commissioners shall serve at its pleasure or for staggered terms of four years subject to removal for cause.