Any appointing authority of the school district may suspend any person within the classified service for any cause for a period of not exceeding 30 days. If any employee in the classified service is suspended by reason of the closing of a school or lack of work to be done, the employee again shall be placed on the eligible list of the civil service board and shall have the first preference in the filling of any vacancy and shall be appointed according to seniority. If the school board opens any closed school, the employees employed in the building shall have first preference to their previous place of appointment.