The Riverside Community College District says the personal information of more than 35,000 students may have been compromised.
The incident happened on May 30 when an employee was trying to send a file containing email addresses, telephone numbers, birth dates and Social Security numbers of enrollees at the Riverside, Moreno Valley and Norco campuses.
Officials with RCCD said the wrong address was entered and the data went to an unsecured site.
Students were sent emails notifying them of the possible data breach this week and the district alerted state and federal agencies as a precaution.
At this point, they don't know if the email address the information was sent to is active or not.
The Press Enterprise reported earlier this week that district officials haven't received any reports of fraud thus far, but they've set up free credit protection services for students for one year to make sure the personal information isn't compromised.
A similar incident happened at College of the Desert on June 5 when an employee sent the Social Security numbers and other personal data of about 1,900 current and retired employees to 78 other employees.
COD officials haven't said how or why that happened, but they did say they've tightened their procedures.