One of the biggest blood testing providers in the country announced Monday that almost 12 million patients may have had their personal, financial and medical information breached. 

Quest Diagnostics was first notified of the breach on May 14. The issue stemmed from the company's billing collections service provider, the American Medical Collection Agency (AMCA). Quest was first notified of "potential unauthorized activity" on May 14. 

AMCA said that the information breached may include personal information, financial data, Social Security numbers and medical information. The company said lab results were not affected. 

Information on which information from which individuals was not immediately available.

"Quest is taking this matter very seriously and is committed to the privacy and security of our patients’ personal information," the company said in a statement. "Since learning of the AMCA data security incident, we have suspended sending collection requests to AMCA."