A group of cybercriminals hacked into data systems at insurance company Aflac, possibly gaining access to sensitive information such as Social Security numbers and health reports, the company said on Friday.

It’s the largest insurance company yet to fall victim to a major hacking, with tens of millions of customers and a $55 billion market cap.

Aflac on Friday disclosed a cybersecurity incident in which personal information of its customers may have been compromised, making it the latest insurance provider to be targeted. The health and life insurance firm said the attack on its U.