A 13-story building that houses the FBI in Salt Lake City has been evacuated because of an envelope containing white powder.

FBI spokesman Juan Becerra says the downtown building was cleared as a precaution around 10:15 a.m. Friday after an employee in the mail room discovered the powder.

Becerra described it as a piece of "hate mail," but he didn't elaborate.

Like all mail received by the FBI, the envelope was placed inside a protective container before it was opened.

Four people in hazardous-material suits entered the building to analyze the powder for any trace of anthrax, which can be fatal.