WASHINGTON (AP) -- Three Senate office buildings were closed Tuesday after a suspicious white powder, apparently delivered through the mail system, was found in the Senate majority leader's office. Officials said several preliminary tests - but not all of them - were positive for ricin, a deadly poison.
More definitive test results were expected later Tuesday.
"This is a criminal action,'' said Sen. Bill Frist, R-Tenn., whose staff discovered the white powder in their Dirksen Senate Office Building mailroom Monday afternoon.
Dirksen and the other two main Senate office buildings were closed Tuesday as authorities were to remove and test all mail that has been delivered there. Senate officials were hoping that process would take only a day, said one congressional official speaking on condition of anonymity.
The closures were forcing the cancellation of committee meetings scheduled for those buildings. But the Capitol was to remain open with the Senate convening Tuesday morning as scheduled.
There were no reports of anyone becoming sick from exposure as of Tuesday morning, the congressional official said.
At least 16 people on the floor were decontaminated, and others who might have been in the area were urged to contact Senate officials, Capitol Police Chief Terrance Gainer told reporters at a late Monday night news conference. The decontamination procedure was not explained, but witnesses saw some people emerging into the cold from a van outside the Dirksen building clad only in T-shirts and pants. One wore a white jumpsuit.
However, no one was expected to get sick, said Frist, who normally uses his Capitol majority leader's office instead of the Dirksen office. If symptoms of ricin poisoning have not surfaced in about eight hours, contamination is unlikely, said Frist, a surgeon before his election to the Senate.
A majority of tests conducted on the powder indicated ricin, Gainer said, even though some were negative.
A clue to ricin poisoning is a suddenly developed fever, cough and excess fluid in the lungs, a fact sheet from the federal Centers for Disease Control and Prevention says. These symptoms could be followed by severe breathing problems and possibly death, the CDC said. There is no known antidote.
Twice as deadly as cobra venom, ricin, which is derived from the castor bean plant, is relatively easily made and can be inhaled, ingested or injected.
Gainer said they were still investigating how the powder got into the mailroom.
The Homeland Security Department was monitoring the situation, spokesman Brian Roehrkasse said. An FBI official said the agency was awaiting a final test from a laboratory at Fort Detrick, Md., before deciding whether to get more fully involved in the case.
Democrat Tom Daschle of South Dakota was majority leader in 2001 when deadly anthrax was found in letters sent to his office and the office of Sen. Patrick Leahy, D-Vt., in the Hart Senate Office Building. No one was ever arrested in those incidents.
Hundreds of Capitol workers, reporters and tourists who were in the Hart building lined up for tests and doses of Cipro and other antibiotics after the anthrax attack. Areas of that building were closed for months for decontamination.
Bob Stevenson, a spokesman for Frist, said the closure of the Senate office buildings Tuesday was "to facilitate collection and removal of unopened mail.''
Stevenson said Capitol tours were being suspended, Senate restaurants closed and Senate pages given the day off. But he said essential Capitol employees were expected to report to work as usual.
The House was scheduled to convene at 12:30 p.m.
Frist gave no indication that extra security had been ordered for the Capitol complex, although security in the area has been high since the Sept. 11, 2001, attacks.
Mail to congressional offices has been irradiated since the 2001 anthrax attack, but Frist said radiation is unlikely to have an effect on ricin.