Anthem Inc., the nation’s second largest health insurer, disclosed Wednesday that hackers had broken into its servers and stolen Social Security numbers and other personal data from all of its business lines. Given the company’s size, this breach could end up impacting tens of millions of Americans.

Anthem didn’t specify how many consumer records may have been breached, but it did say all of the company’s business units are affected. The figures from Anthem’s Web site offer a glimpse at just how big this breach could be: “With nearly 69 million people served by its affiliated companies including more than 37 million enrolled in its family of health plans, Anthem is one of the nation’s leading health benefits companies.”

The company said it is conducting an extensive IT forensic investigation to determine what members are impacted.

“We are working around the clock to determine how many people have been impacted and will notify all Anthem members who are impacted through a written communication,” Anthem said in question and answer page released about the breach.

Formerly known as Wellpoint Inc., Anthem said in a statement that the company was the target of a “very sophisticated external cyber attack” that exposed names, dates of birth, member ID/ Social Security numbers, addresses, phone numbers, email addresses and employment information. The company stressed that the exposed data did not include medical records or financial information.

According to Athem’s statement, the impacted (plan/brands) include Anthem Blue Cross, Anthem Blue Cross and Blue Shield, Blue Cross and Blue Shield of Georgia, Empire Blue Cross and Blue Shield, Amerigroup, Caremore, Unicare, Healthlink, and DeCare. The company said impacted members will receive notice via mail which will advise them of the protections being offered to them as well as any next steps.

Anthem said once the attack was discovered, the company immediately made every effort to close the security vulnerability, contacted the FBI and began fully cooperating with their investigation.

More on this story as it develops. Stay tuned.