BLACKSBURG, Va. — Nearly three years after a massacre that left more than 30 dead, Virginia Tech officials are urging calm as e-mails and Internet postings originating in Italy threaten another attack on campus.

Though police do not believe the threats are credible, University President Charles W. Steger said in an e-mail to faculty and students Wednesday that classes would be held today with additional security across campus.

Given the public concern, Steger said an overabundance of caution is appropriate.

“Given all that this university has endured, I can understand how this can be very upsetting to the university community,” Steger wrote in the e-mail. “Remember that we are a community that cares for each other and I ask that you continue to support each other.”

University spokesman Larry Hinker said there had been no new, substantive developments today, but the school felt it was important to communicate to the community that authorities were investigating the threats.

“Obviously, some of the students who had gotten this were a little rattled and there was an awful lot of rumor-building,” Hinker said.

Hinker could not provide an exact number of police on campus today, but said the increased security was noticeable.

Authorities investigated similar threats earlier this month and in October and believe the new posts are from the same person.

A YouTube user had created a Web page under the name “nextvirgtechkiller” that included the statements “the massacre is incoming” and “next massacre is incoming.” The person officials believe to be responsible also has continued to send threatening e-mails to students and employees over the last several days, Steger said in the e-mail.

Virginia State Police and the FBI are assisting in the investigation.

Virginia Tech was the scene of the worst mass shooting in modern U.S. history in April 2007. Student Seung-Hui Cho killed 32 people on campus, then committed suicide.