Social security numbers of students registered for fall 2008 classes, totaling nearly 24,000, were inadvertently printed on mailing labels for a parking brochure, the Department of Transportation Services said in an e-mail to students today.

“The University apologizes, and deeply regrets this unfortunate mistake. We are taking aggressive steps to ensure that this does not happen again. We strongly recommend that you take appropriate precautions to mask, black out, or destroy this document after use,” said the e-mail, signed by DOTS Director David Allen.

The mailings were sent July 1, but the mistake was not discovered until July 8, when students began calling DOTS to complain, according to a website set up by DOTS specifically for this incident. The website can be found at http://www.transportation.umd.edu/parkingmailer/.

The university is not aware of anyone’s social security number being misused, added DOTS in the e-mail.

The university will offer free Equifax reports to affected students, at a cost to the university of about $23 a person, said Vice President for Student Affairs Linda Clement. With Equifax, the students can monitor their credit or place a fraud alert on their account.

Clement explained that when a DOTS employee collected names and addresses for the brochure, social security numbers and e-mail addresses would have appeared in the search, but were supposed to be removed from the labels. DOTS saw the e-mail addresses on the labels but didn’t identify the social security numbers because they were not separated by the typical two dashes, she said.

The incident is under investigation and the person involved has not been fired, Clement added. The delay in notifying students was due to the legal office negotiating a deal with Equifax.

“We sincerely regret it,” Clement said. “This is just an awful situation; we’re trying to do everything we can to mitigate it.”

A letter explaining the situation and offering remedies will be sent to students Friday or Saturday, said Ann Wylie, the university president’s chief of staff.

“We were horribly upset that this happened,” she said. “It was a human error.”