Someone hacked into the computer system that serves Ohio University's alumni relations office and took control of the biographical information of more than 300,000 persons, including the Social Security numbers of 137,000 of them.

In e-mails and letters sent Wednesday extending "deep regrets" to its alumni, including 2,445 in Western Pennsylvania, an administrator said the breach "dates to March 1, 2005, or prior" but wasn't discovered until 12 days ago.

"We know that during this period intruders had control of the system and uploaded and downloaded large quantities of data," wrote Molly Mayo Tampke, interim vice president of university advancement. She said the data didn't include credit card or bank information. She said the FBI is investigating.

"In response to this attack, Ohio University is taking every precaution to protect the data on its live servers, including hiring an outside consultant to perform a comprehensive risk assessment of our entire environment to ensure that such a breach does not happen again," Ms. Mayo Tampke added.

"We are doing everything in our power to reduce the impact of this data theft," Bill Sams, the university's associate provost for information technology and chief information officer, said in a news release posted on the school's Web site, www.ohio.edu.

"At this point, we have no evidence of illegal use of the breached information," Mr. Sams said. He said the university is using "all available resources" to identify the extent and source of the breach.

"Once it became clear that personal information was involved, we began the process of notifying the affected individuals," Mr. Sams said. In those notices, the university offered recommendations on what steps the recipients should take to protect themselves.

The university said in its e-mail and letters that it won't solicit personal information from the recipients as part of its response to the incident.

"If you are contacted [by e-mail, letter or telephone] by someone claiming to represent the university who then asks you to provide personal information, do not do so," it warned.

He said the university has set up a Web page at www.ohio.edu/datatheft to provide detailed information for people potentially affected by the theft of information. There also is a toll-free hot line -- 1-800-901-2303 -- for those who were affected or who are uncertain if their information was illegally accessed.

In its e-mail and letters, the university strongly urged the recipients to be alert for signs of possible misuse of their personal identity. It said they can place a fraud alert on their credit report by contacting any of these consumer reporting companies:

Equifax, 1-800-525-6285, www.equifax.com, P.O. Box 740241, Atlanta, GA 30374-0241; Experian, 1-888-397-3742, www.experian.com, P.O. Box 9532, Allken, TX 75013; TransUnion, 1-800-680-7289, www.transunion.com, Fraud Victim Assistance Division, P.O. Box 6790, Fullerton, CA 92834-6790. Only Experian has an online fraud alert form.

Mr. Sams said current students haven't been affected by the incident.

In what the university described as "an apparently unrelated incident of data theft," the FBI notified the university on April 21 that the server containing the office files of its Technology Transfer Department had been compromised.

The data on the server included e-mails and patent and intellectual property files. The disk drives from the server were given to the FBI.

Boston College, California State University, Iowa State University, the University of Texas at Austin, the University of Connecticut and Stanford University have experienced security breaches in the past year.