Muir Medical Group patients who received treatment between November 2013 and February 2017 may have had their personal information shared without their consent, the company reported.
The Walnut Creek-based firm discovered the leak on March 7 after a former employee took information with her before her employment ended, according to the company.
This information included medical information, such as diagnoses, test results, medication and other treatment info. It also included names, social security numbers, addresses and contact details.
Read more on NBC Bay Area.