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, a U.S. insurance provider that covers millions of policyholders, warned some of its customers' most sensitive data may have been stolen in a recent cyberattack. Why it matters: Aflac warned that a "sophisticated cybercrime group" was behind the intrusion and said many insurance providers are currently battling the same group.