A county in Washington inadvertently released nearly half a million partial Social Security numbers when responding to a routine public records request in December, according to county officials.

The Pierce County Auditor's Office, which mistakenly released the sensitive data, said in a news release that the error was quickly spotted and that the person who accidentally received the SSN digits deleted them within two hours. The requester had not asked for the personal information, the auditor's office said.

"First let me say that I am incredibly sorry that this happened," Pierce County Auditor Linda Farmer said in statement. Farmer added that this was not a targeted hack but an employee error, and that "we have taken steps to ensure it does not happen again."

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The partial Social Security numbers were sent out in a spreadsheet of voter registration data, an otherwise routine records request for publicly available voter information including names, addresses and birth dates.

Social Security numbers, which can be used to commit identify theft and other types of fraud, are exempt from public disclosure by state and federal law.

WA private information leak

Almost half a million partial Social Security Numbers were inadvertently released by Pierce County, Washington. 

In a Jan. 17 letter sent to the 463,110 voters affected, Whitney Stevens, the public records officer for the auditor’s office, apologized and outlined steps those impacted can take to protect their private information and monitor for fraud.

Photos of the letter circulated on Twitter alongside confused and sometimes annoyed comments from those affected by the lapse.

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"We have confirmed that there was no widespread dissemination of information and no retention or copying of the information by the requester," Stevens said. "We encourage you, as always, to remain vigilant and monitor your account statements, insurance transactions, and free credit reports for potential fraud and identity theft, and promptly report any concerns."

In response to question from the The News Tribune, spokesperson for Pierce County Libby Catalinich said the county is now requiring information to be reviewed by a second employee before being released to the public.

Catalinich did not immediately respond to a request for comment from The Associated Press.