Aflac, one of the largest insurance companies in the United States, says hackers stole an unknown quantity of its customers’ personal information from its network during a cyberattack earlier this month.

Insurance company Aflac disclosed this week that cybercriminals breached its U.S. network and may have accessed customers’ personal information, the latest in a string of cyberattacks on insurance companies announced this month.

Aflac Inc. said a recent cybersecurity breach could have given intruders unauthorized access to customers’ personal information, including Social Security numbers, as well as health and claims data.