BRIGHTON — Just before St. Patrick’s Day more than 100,000 alumni of Boston College alumni received a message from their alma mater, but it certainly wasn’t the cheerful “Erin Go Bragh” they may have wished for.

Beginning March 11, the college mailed letters to alumni informing them that earlier in the week a computer containing their personal information had suffered a security breach by hackers. The information was being stored for use in alumni fundraising efforts.

According to BC spokesman Jack Dunn, the college’s information technology department discovered the breach after noting a spike in activity on the computer.

Dunn said the computer was immediately taken offline and secured. A subsequent computer forensics investigation determined that the personal information was not the target of the hacker attack and that none of the information had been compromised.

“We were very fortunate,” Dunn said.

Nevertheless, as a precaution, the college sent a first-class letter to each of the more than 100,000 alumni whose information was stored on the computer, informing them of the security breach.

“Even though no personal information was accessed we decided to alert alumni,” said Dunn.

According to Dunn, the investigation concluded that hacker apparently intended to use the BC computer as a base to launch attacks on other computers on the Internet. There was no indication as to why this particular computer was targeted.

In addition to the letter, BC has established a special Web site and hotline to address questions related to the security breach.

The Web site, www.bc.edu/alert, provides information on how alumni can verify that their credit records do not contain fraudulent information and what steps to take if they believe their personal or financial information has been stolen.

The toll-free hotline, 866-683-6369, is staffed by Boston College employees ready to answer alumni questions on the issue.