Updated

A bomb threat targeting Ohio State University was e-mailed to the FBI Tuesday morning, prompting the school to evacuate four academic buildings, including the main library. An initial search turned up nothing out of the ordinary, officials said.

The threat was in a message received Tuesday at FBI headquarters in Washington, said Paul Bresson, an agency spokesman based there. Campus police said they were alerted at 8:19 a.m. Tuesday that the threats involved the William Oxley Thompson Memorial Library and three laboratory buildings.

"This is still in our assessment a threat, and there have been no suspicious package or devices found at this time," university Police Chief Paul Denton said at a news conference.

Authorities did not identify the source of the bomb threats at Ohio State, one of the nation's largest universities, with more than 56,000 students at its main Columbus campus. The FBI's Bresson declined to provide information about where the e-mail appeared to come from or whether the bureau believed the threat was real.

University officials did not offer information on the nature of the threats and declined to speculate on why the four buildings were targeted.

All were evacuated and closed as investigators went through them with bomb-sniffing dogs, and authorities also closed off three streets.

"It's a little worrisome. Maybe there won't be a warning next time," said Todd Elder, 21, a psychology major from Columbus.

Staff members outside one of the labs had thought they were being evacuated for a routine fire drill. Many left purses, coats and car keys in their offices and were stuck waiting for hours in the cold rain.

Art history professor E. Okechukwu Odita was stranded because his car was parked behind police tape.

"I appreciate what they are doing. We don't want the whole place to blow up," Odita said, as he waited on a bench near the labs.

Some students standing outside the labs joked that the threat may have been called in by someone who just wanted to miss an exam.

Students and faculty members were warned by text-message alerts and online and phone messages to stay clear of the buildings until 5 p.m. The buildings would remain closed at least until that time, with their regular classes and other activities canceled, said Vernon Baisden, the university's director public safety. Baisden could not specify how many students were affected by the evacuations.

All other classes and functions on campus will continue as scheduled, Baisden said.

The Columbus Fire Department bomb squad, school security and FBI were at the scene.

Besides the library, which is along the campus green area called The Oval, buildings closed were McPherson Chemical Lab, which houses the chemistry and astronomy departments; Smith Laboratory, which houses engineering experiments and anthropology; and Scott Laboratory, a mechanical engineering building.

The bomb threats marked the second time in a less than a week that a criminal investigation disrupted activities at an Ohio college campus.

Students at Kenyon College, about 60 miles north of Columbus, were subjected to a nearly nine-hour lockdown from Thursday night into Friday morning after a truck belonging to a woman who disappeared along with her two children and a female friend was found nearby.

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