FRESNO (CBS SF) – A data breach at Fresno State University may have compromised the personal data of up to 15,000 people, the school announced Tuesday.

According to a university statement, the data breach stemmed from a break-in at the school’s athletic department while the campus was closed for the holidays. In early January, the school discovered an external hard drive was stolen during the break-in.

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Officials determined that the hard drive may have contained information on former student athletes, attendees of sports camps and Athletic Corporation employees. About 300 of the 15,000 people possibly impacted are currently affiliated with the university.

Compromised data may include names, addresses, phone numbers and dates of birth, along with Social Security numbers, driver’s license numbers and passport numbers.

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“Though this appears to be an isolated incident, we take any data theft very seriously and will review campus policies to ensure we have best procedures in place when it comes to security of confidential and sensitive data,” chief information officer Orlando Leon said.

The university said the stolen information has not been accessed or misused so far. An investigation into the break-in and data breach is ongoing.

School officials began contacting affected individuals on Tuesday. Free credit monitoring for one year will be offered to people whose Social Security number, financial account information or driver’s license number was exposed.

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Anyone with concerns about the data breach is asked to call the school at 877-646-7924.