SAN DIEGO (CNS) - San Diego City Attorney Mara Elliott Wednesday announced a lawsuit against consumer credit agency Experian for allegedly causing harm to millions of people, including a quarter-million residents of San Diego County, when it failed to notify those whose identities had been stolen by hackers.

Experian harmed some 3.1 million consumers, including 250,000 in San Diego County, when it failed to protect their personal information from being exposed to identity thieves on the dark web, according to the suit.

Consumers' social security numbers and credit card security codes were among the data compromised during the breach, which began in 2015 and lasted over an 18-month period, Elliott said.

"Experian then broke the law by not telling these consumers the truth about what happened," Elliott said.

Elliott said hackers obtained $65 million in fraudulent tax returns as a result of the breach.

California law requires companies to notify victims of security lapses that put that risk by exposing their personal information, she said.