The selectmen, except as provided in the three preceding sections, may establish a fire department, and thereafter shall annually, in April, appoint a suitable number of engineers, not exceeding twelve, for one year from the following May first, and until others are appointed in their stead; may, for cause, remove an engineer, after seven days' notice to him and a hearing, and shall fill all vacancies.
Mass. Gen. Laws ch. 48, § 45