Thirty-one thousand patients and staff are at risk of identity theft after two laptop computers disappeared from Seattle-based insurer Group Health Cooperative. The computers stored personally identifying information, including names, addresses, and Social Security numbers, the insurer announced March 23.

A Group Health investigation has not yet turned up the missing computers. Although the insurer did not provide detailed circumstances of the breach in its release, it did say that both machines are password-protected.

Group Health will also be contacting victims of the breach and will offer free credit monitoring services.