Can we terminate a new employee who is out on injury leave?

Q. After hiring a new employee in November 2011, she developed serious back trouble that was not work-related. She would come to work in obvious pain and taking pain medication. Most of her admin job involved sitting down, however there was filing, and trips to the Fedex box and normal movement that she was having difficulty doing. One weekend in January, her mother called to tell me the employee was in the emergency room unable to move. She has not returned since and her doctor placed her on total disability. We have had to hire someone in order to operate our seven-employee business. So, what are my obligations to her legally after three months of employment?  I would like to tell her there is no position here for her. - Tom, California