DALLAS—Computer hackers may have accessed Social Security numbers and other personal data for 9,100 people connected to the University of Texas at Dallas, the school’s second such case in recent years.

School officials told The Dallas Morning News on Thursday it was unclear whether hackers actually viewed the information, but names, addresses, e-mail addresses and telephone numbers were exposed.

The breach was discovered July 12 by the university’s computer security staff. UTD did not alert those affected until Thursday because it took time to determine exactly whose data may have been exposed, officials said.

“The reason we discovered this is because they were on the job, they look for it,” Susan Rogers, UTD’s vice president for communications, told the newspaper. “Every day, computers in university systems are subject to constant battering from external sources who are trying to get in. Security is a constant issue.”

Students, faculty members and staff whose personal information is at risk are being contacted by e-mail and letter. The majority of those affected were 4,406 students who were on the Dean’s List or graduated between 2000 and 2003. The school also reported that information for 3,892 students who were contacted to take part in a survey by the Office of Undergraduate Education in 2002 was exposed.

The information was collected and saved before UTD stopped using Social Security numbers and began creating its own system to identify students and school personnel. The information was stored on a computer hard drive.

In December 2006, names and Social Security numbers of up to 35,000 faculty, students and staff may have been exposed to hackers. No arrests were ever made in that case.