Quest Diagnostics says nearly 12 million of its patients may have had their personal, financial and medical information breached.

American Medical Collection Agency, a billing collections service provider, informed Quest Diagnostics about the data security incident.

According to the company, someone had unauthorized access to their systems between last August and this past March.

The company still hasn't received the full details on the breach. 

Quest Diagnostics is one of the biggest blood testing providers in the U.S.

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