WASHINGTON (AP) _ Authorities closed an entire wing of an eight-story Senate office building Tuesday and prepared to test and treat hundreds of people for possible exposure to anthrax after overnight tests confirmed the bacterium in mail opened in the office of Majority Leader Tom Daschle.

``There will be several hundred people that will be screened today,'' said Dr. John Eisold, the attending physician at the Capitol. All of them will receive enough antibiotics to cover them until the results of their tests are known.