About 3,500 people were evacuated from a Brigham Young University building Monday after a threat that officials now speculate came from a student trying to avoid taking a test.

University Police received a telephone call about 10:15 a.m. from a person who said something would happen in the Jesse Knight Humanities Building within an hour. The caller did not specify the danger, said Paul Richards, university spokesman.Officials waited until 11 a.m. to clear the building. They sounded the fire alarm and assisted students, faculty and staff members outside, where they waited about 20 minutes while police and physical facilities workers searched the building.

No evidence of danger was found, and Richards said police were fairly confident when they received the call that it was a hoax, but because so many people were in the building they decided to play it safe. Buildings are not always evacuated when the university receives threats.

"When you have that many people in there it's a big responsibility," Richards said. "Just leaving the people in the building would have made guinea pigs of them."

Brigham Young University gets one to two threatening phone calls every year, Richards said, usually during final exams or midterms, as was the case Monday.

"We're pretty sure it was just some prankster who didn't want to take an exam. It was really frustrating, because there were a lot of handicapped people in there," he said. "We had no idea what was there or where, so it took more time, more wasted time."

Such pranks cost the university money, Richards said, because employees are being paid while they stand outside and police have to leave their other duties to investigate the problem.

Officials will use a recording they made of the threatening call to try to track down the person who made it, but Richards said it's like "looking for a needle in a haystack" unless the person makes a habit of such calls and establishes a pattern police can follow.

University officials' greatest worry now is that there will be a rash of copycat incidents as tests continue through next week.