(Bloomberg) — Hackers may have breached a database withinformation on 1.1 million customers of CareFirst BlueCrossBlueShield, a health insurer operating in Maryland, Virginia andthe District of Columbia.

The breach happened last June, when hackers targeted a databasethat contained information customers used to log on to CareFirst'swebsite, the not-for-profit health insurer said in a statementWednesday.

They may have obtained names, birth dates, e-mail addresses andsubscriber identification numbers, the insurer said. The databasedidn't have passwords, Social Security numbers, credit cardinformation or medical records.

CareFirst said a review by the security firm Mandiant Corp.didn't find evidence of any other breaches.

Hackers are increasingly targeting medical information, inparticular from health insurers, which can offer a wealth of dataincluding health, financial and identity information.

In February, the health insurer Anthem Inc. said hackersaccessed data on about 80 million people. In March, Premera BlueCross, which operates in the northwestern U.S., said information on11 million people may have been exposed.

To protect customers, CareFirst said it will offer victims twoyears of credit and identity theft monitoring. It's also askingthem to set up new user names and passwords.