The County assumes no liability for injury or death of emergency management volunteers in the performance of their duty as such volunteers, except that which is imposed by State law or by this Code or other ordinance or resolution of the County Council; provided, however, that emergency management volunteers assigned to duty during a period of natural disaster in the County shall be eligible for the benefits of the State Workmen's Compensation law at a rate of compensation commensurate with that of persons performing similar work under conditions of regular employment.