Is an employer liable to a third person for negligence in hiring or retaining an employee who is incompetent or unfit?

"An employer may be liable to a third person for the employer's negligence in hiring or retaining an employee who is incompetent or unfit." (Roman Catholic Bishop v. Superior Court (1996) 42 Cal.App.4th 1556, 1564.) Negligence liability will be imposed upon the employer if it "knew or should have known that hiring the employee created a particular risk or hazard and that particular harm materializes." (Doe v. Capital Cities (1996) 50 Cal.App.4th 1038, 1054.)