WASHINGTON (AP) A District of Columbia postal worker is "gravely ill" from inhalation anthrax, a rare and lethal form of the disease, officials said yesterday, and five others are sick with suspicious symptoms. The Postal Service closed two facilities and began testing more than 2,200 workers for exposure.

The diagnosed man, who was not identified, is the third person in the nation to come down with the most serious form of the disease, where anthrax spores enter the respiratory system and lodge deep in the lungs. Six others, including two postal workers in New Jersey, have been infected with a highly treatable form that is contracted through the skin.

Mayor Anthony Williams said the latest victim, the first in Washington to contract the disease, was "gravely ill." He was listed in serious but stable condition at a suburban Virginia hospital near his home.

Five other District postal workers have symptoms that are consistent with anthrax and health officials are awaiting the results of testing to determine if they actually have the disease, said Jack Pannell, spokesman for the city health department.

At least two of them are hospitalized, Pannell said.

As postal workers lined up for testing in Washington, the number of people directly affected although not sickened by the anthrax-by-letter scare reached well above 5,000 just in the nation"s capital. Investigators focused on Trenton, N.J., where some of the tainted letters were mailed.

Meantime, congressional leaders said they would reopen the Capitol today, though House and Senate office buildings will remain closed until results from environmental testing are complete.

The closures were prompted by an anthrax-laced letter that arrived a week ago at Senate Majority Leader Tom Daschle"s office. It was processed at the central mail processing facility where the latest victim worked, but officials said they did not know whether the worker came into contact with the letter or whether there might have been other tainted letters that have yet to be discovered.

The man first developed flu-like symptoms in the middle of last week but did not feel ill enough to go to the hospital until Friday. Sick with fever and chest pain, he was immediately given Cipro and other antibiotics, but health officials did not know whether they began treatment early enough to save his life.

Surgeon General David Satcher said inhalation anthrax which is not contagious has been fatal about 80 percent of the time. "But that"s in the past. We have different technology today," he said on CNN"s "Late Edition. "It is not yet hopeless."

It was unclear how ill the man was yesterday, though a postal official said he was alert enough to watch the Washington Redskins game on TV.

Health investigators moved quickly to determine whether anthrax was present in either of two postal facilities where the man worked and whether other employees might have been exposed.

More than 2,100 workers at Washington"s main mail processing center and 150 at an air mail handling center near Baltimore-Washington International Airport were asked to report for nasal swab testing, which will help determine where in the buildings exposure may have occurred. Employees will each be given a 10-day supply of antibiotics to ward off infection in case they were exposed.

The testing began at City Hall yesterday, an hour after officials confirmed the diagnosis. It was to continue today at D.C. General Hospital.

"God forbid if more comes through," said Larry Bagley, who works near the hospitalized worker and was lined up for testing. "I feel I"m all right. I have faith in God and the Cipro."

Officials also planned extensive environmental testing at both facilities. They will use the results, along with nasal swab testing of employees, to determine which workers will need a full course of preventive antibiotics.

The victim worked in a small room and did not typically come into contact with the large mail sorting machines, said Deborah Willhite, a top Postal Service official. She said it was unclear how he might have inhaled enough anthrax at least 8,000 of the invisible spores to contract the inhalation form of the disease.

After the Daschle letter was discovered, the Postal Service hired independent contractors to test the Washington facility for anthrax. Officials still were awaiting the results, Willhite said.

Both facilities will be closed until testing and cleaning can be completed, she said.

On Capitol Hill, an environmental sweep through 19 buildings continued yesterday. Investigators have found traces of anthrax in four of them, and 28 people have tested positive for exposure, though none has been diagnosed with the disease.

Last week, the House shut down operations for the first time in history to allow for the sweep.