An undisclosed threat at the University of British Columbia temporarily closed down one of the school's biggest buildings on Wednesday.

The Biological Sciences building -- in the heart of the university's main campus in Vancouver -- was locked down for a short time in the afternoon because of what police called a "threat to public safety."

Police did not state the specific nature of the threat, but students were not allowed in or out of the building in the afternoon unless they were escorted by the RCMP.

One student, whose lab partner was in the building at the time of the lockdown, told CTV British Columbia that "an administrator had told them not to open the door until they came around with a password signaling that they could leave the lab." Another student said he was "freaked out."

At about 2:30 p.m. the university issued a campus-wide bulletin telling students not to leave the buildings they were in. At one point, UBC President Stephen Toope sent out an email to faculty and staff stating that people who did not have to come to campus should stay away.

Although that bulletin was lifted a short time later, it was a tense situation for part of the school day. The Emergency Response Team had been called in and dog teams were on the scene.

The RCMP's major crimes unit was also dispatched, along with a police explosives team. A helicopter was also reported hovering above the building.

The lockdown request was lifted in the late afternoon. Police then went floor-by-floor throughout the building and escorting people out of the building. By late Wednesday night, police had still not said what specifically caused the lockdown.