NEW YORK (AP) — Premera Blue Cross, a health insurer based in the Pacific Northwest, says it was the victim of a cyberattack that could affect 11 million people.

The company says hackers gained access to its information technology systems. The breach could have exposed members’ information including names, dates of birth, Social Security numbers, mailing and email addresses, phone numbers, member ID numbers and bank account information.

It says claims information, including clinical information as well as the personal information of people who did business with Premera, could also have been exposed.

The Mountlake Terrace, Washington, company says it has not found evidence that data was removed from its systems or that customer information has been used inappropriately.

The attack occurred May 5 and Premera discovered it Jan. 29.