§ 7424. Prohibition on discrimination. No employer shall discriminate against an employee because the employee has been injured in the line of duty as a volunteer fireman, a volunteer member of the fire police or a volunteer member of an ambulance service or rescue squad, nor shall an employer discriminate against an employee injured in the line of duty as a volunteer fireman, a volunteer member of the fire police or a volunteer member of an ambulance service or rescue squad who subsequently returns to work after receiving workers' compensation benefits under the act of June 2, 1915 (P.L.736, No.338), known as the Workers' Compensation Act.