Virginia officials say 639 individual Social Security numbers were potentially made public, and they have taken steps to ensure the information is secure and no longer available.
The Department of General Services said Friday it will review information from agencies where the data originated to determine how the database breach occurred.
Spokeswoman Susan Pollard said the numbers would have been accessible only to someone who accessed the department's website.
The department said it will contact individuals who potentially had their Social Security numbers accessed to explain what occurred and what actions they can take to monitor their credit information. A central telephone number will be provided next week for individuals to call and learn more.
General Services Director Richard Sliwoski called the security breach "troubling."