Editor's note: This article has been revised to reflect the following correction, which will appear in Tuesday's print edition. The male graduate student who wore a mask to the old biology building Friday morning, prompting Georgia Southern University police to close that building and two connected ones in response to what they termed a "suspicious person" who presented a "credible threat," could still face the possibility of criminal charges. Because of a reporting error, a front-page article Saturday incorrectly said the student would not be charged. The Statesboro Herald regrets the error.

One student's prank led police to lock down portions of Georgia Southern University Friday morning, but the culprit was not arrested.

University officials did not release details of the prank except that the offender wore a mask.

A male student wearing a mask and dark clothing was spotted around 8 a.m. "walking inside of the Math, Physics and old Biology building" on Georgia Avenue, according to a university news release issued Friday afternoon.

A short time later, Georgia Southern police responded to the scene and alerted students, faculty and staff about the incident via an Eagle Alert and other forms of communication. Officers evacuated the old biology building, and other nearby buildings were placed on lockdown for a short time as a precaution, the release says.

In a brief news conference at about 10:30 a.m. Friday, University Police Chief Michael Russell said those buildings were locked down after university police received "what we felt was a credible threat" specific to that area.

The Eagle Alert issued shortly after 8 a.m. had indicated there was a "suspicious person" in the area of the old biology building.

Russell explained to reporters in the midmorning news conference why some police officers behind him appeared to be suiting up with specialized equipment.

"We have some officers that are cross-trained in tactical activities," he said. "And they have tactical equipment, and they're going to be carrying those in with them as well."

During the news conference, yellow crime-scene tape roped off Herty Drive just in front of Hanner Fieldhouse and extended into the woods to the old biology building.

Students and staff in the old biology building were asked to seek safe shelter where they were, and others were instructed to avoid the area.

"No weapon of any kind was involved in the incident," the release says.

Other parts of campus appeared to be operating normally even while the investigation was at its most intense, with students walking and bicycling around to get to their classes.

"Although everybody is in a little heightened sense of awareness, the rest of campus, I can't say is unaffected" but was not subject to a lockdown, Russell said.

Georgia Southern police, with assistance from several other agencies, including the Statesboro Police Department, Bulloch County Sheriff's Office, Bulloch County EMS, Georgia State Patrol, Georgia Bureau of Investigation and FBI, secured the building and performed a safety sweep.

"Our team acted swiftly by immediately responding, cordoning off the area and evacuating the building," Russell said. "Students, faculty and staff were notified within minutes by phone, text and email that there was an incident on campus and to stay put while officials investigated."

Police received a tip that a graduate student was involved, according to the university's statement.

"Upon further investigation it was confirmed that a student wore the mask as a prank and did not intend to cause alarm," the release says.

Police gave the "all clear" around 12:30 p.m. University police "will continue to investigate the incident," according to the release.

"It's a good training exercise," Russell said. "It's the best kind of training exercise. We didn't have to spend three weeks going to meetings to prepare what to do. We just react accordingly. I was pleased with our response."

Classes resumed in the Math, Physics and old Biology building, and arrangements were made for students affected and inconvenienced by the incident and subsequent evacuation, the statement says.

Staff Photojournalist Scott Bryant contributed to this report.

Holli Deal Saxon may be reached at (912) 489-9414. Jason Wermers may be reached at (912) 489-9431.