The personal information of approximately 15,000 New York City Transit Authority workers has been found on a compact disc inside a refurbished computer sold by a retailer.
Authorities are investigating how the CD found its way into the computer drive.
The Associated Press obtained a letter about the security breach from one of the affected employees.
The letter dated March 6 says there is no immediate indication that any of the information on the CD was copied. It says the New York Police Department is investigating.
An authority spokesman referred a reporter to the content of the letter for comment. It described the breach as a "singular event."
Employees and retirees have been told they are being provided with a year of free credit monitoring.
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