A person employed by the department who is injured as a result of an assault by a recipient of mental health services shall receive his full wages by the department until workmen’s compensation benefits begin and then shall receive in addition to workmen’s compensation benefits a supplement from the department which together with the workmen’s compensation benefits shall equal but not exceed the weekly net wage of the employee at the time of the injury. This supplement shall only apply while the person is on the department’s payroll and is receiving workmen’s compensation benefits and shall include an employee who is currently receiving workmen’s compensation due to an injury covered by this section. Fringe benefits normally received by an employee shall be in effect during the time the employee receives the supplement provided by this section from the department.