SEATTLE (AP) — Authorities say five people have been indicted on charges they hacked Target Corp. gift cards to the tune of nearly $800,000.

The U.S. Attorney's Office in Seattle says the group devised an algorithm that could identify a gift card's bar code, then used the company's automated customer service telephone system to find cards with balances. According to investigators, the suspects loaded those balances onto electronic wallet or mobile phone apps, redeemed them at Target stores, and sold the items they purchased for bitcoin.

Prosecutors say the thefts took place at stores in Washington, Oregon, California, Nevada and Colorado. Target changed its gift card system last December in response.

Two defendants pleaded not guilty Tuesday, and one is in state custody on other charges. Authorities say they are searching for two other defendants, 22-year-old Kennady Weston and 26-year-old Derrick Quintana, both of Everett, Washington.