No person under 16 years of age shall be employed, except in agricultural service, and except as otherwise provided in this chapter. Any person 14 or 15 years of age may be employed outside school hours and during school vacation periods, so long as the person is not employed in, about, or in connection with, any manufacturing or mechanical establishment, cannery, mill, workshop, warehouse, or machine shop or in any occupation or place of employment otherwise prohibited by law. The presence of any person under 18 years of age in any restricted business establishment or restricted occupation shall be prima facie evidence of his or her employment therein.