Gannett, the publisher of USA Today and other newspapers, has warned about 18,000 current and former employees that hackers may have had access to their personal information after breaking into the emails of members of its human resources department.

The company says there is no indication sensitive information was taken, but it can't be sure.

Gannett says it learned in March that several people in its human resource department were victims of a phishing attack, in which hackers try to steal through emails. It says hackers accessed email accounts and were able to send other phishing emails from there. There was also an unsuccessful attempt to wire transfer corporate money.

Gannett Co., based in McLean, Virginia, says it has notified authorities.