Woodland Hills, Calif.-based health insurer Health Net announced Monday that it had lost servers containing personal health information and demographic data for nearly 2 million current and past patients.

The breach, which affects approximately 1.9 million people nationwide, occurred in February. Health Net said it cannot account for server drives missing from a data center in Rancho Cordova, Calif. Those drives contain patients' names, Social Security numbers and sensitive health information. It's not the first time Health Net enrollees have experienced a breach. In 2009, 1.5 million people were affected when a portable hard drive containing patient data went missing.

According to the California Department of Managed Health Care, the breach will affect as many as 845,000 of the state's residents. In a news release, Connecticut Attorney General George Jepsen urged the insurer to provide adequate identity protections for the 25,000 state residents whose data has been compromised.

"Health insurance companies have access to very sensitive and personal information," Jepsen said in the release. “They have a duty to protect that information from unlawful disclosure.”

In a news release, Health Net said it would offer two years of credit monitoring and identity protection to affected customers. The insurer also has set up a hotline.