In the event of the death, resignation, or removal from office of the mayor and board of aldermen or commissioners, or a majority of the aldermen or commissioners, so that said vacancies cannot be filled as now provided by law, it shall be the duty of the governor to fill such vacancies by appointment for the unexpired term where such unexpired term is less than six months, and if more than six months, until an election can be held as now provided by law to fill such vacancies.