A computer virus attack may have exposed the personal information of more than 11,000 people who donated to a Central Oregon hospital system.

Hospital officials say it is not clear whether any of the information was seen by individuals outside the hospital, the Bulletin reported. The hospital announced Wednesday that the virus may have exposed the information.

The virus penetrated the computer system Dec. 11, and the hospital’s information technology staff believed they had rebuffed it. But Feb. 5, they detected suspicious activity in the system and called in computer forensic experts to investigate. By Feb. 20, it became clear the information had been made vulnerable by the virus.

“Although the investigation provided no indication that information was misused, CHC is working quickly and diligently to provide all affected members of our community with leading credit monitoring services at no charge,” said James A. Diegel, FACHE, President and CEO of CHC.

“We want to express our sincere apologies to those community members who have trusted us with their information for the inconvenience and worry this situation may have caused.”