WASHINGTON (AP) - Officials confirmed anthrax Tuesday as the cause of death of two postal workers in the nation's capital, the latest victims in the nation's bioterrorism scare. A mail handler in New Jersey also was believed suffering from the disease.

"We need to treat and to treat quickly," said Dr. Ivan Walks, the senior health official in the District of Columbia, adding that anthrax had been confirmed inside the central Brentwood mail facility that serves the entire city. Antibiotics were being dispensed to postal workers across Washington as officials began testing to see if anthrax spread to local post offices.

Two more people affiliated with the Brentwood facility are being treated for inhalation anthrax, though test results confirming the diagnosis are not complete, said Donna Bigler, spokeswoman for Montgomery County, Md., where the two patients are hospitalized.

One of them, a 35-year-old man, works at Brentwood. The second, a 41-year-old woman, is a postal union official and was in the facility regularly, Bigler said.

Local health officials said two other cases showed symptoms of inhalation anthrax.

Buffeted with questions, White House spokesman Ari Fleischer defended federal health authorities who initially opted not to test the Brentwood facility after learning it had handled an anthrax-tainted letter sent to Senate Majority Leader Tom Daschle.

"The president believes the cause of death was not the treatment made by the federal government or the local officials, or anyone else, but the cause of death was the attack made on our nation by people mailing anthrax," he said.

Defending his agency, Dr. Jeffrey Koplan, director of Center for Disease Control and Prevention, said the CDC never suspected that anthrax could leak out of a sealed letter.

"We had had no cases of inhalation anthrax in a mail sorting facility," he said. "There was no reason to think this was a possibility."

At the same time, Health and Human Services Secretary Tommy Thompson said that if additional tainted letters are found, officials would move more aggressively to test and treat any workers at postal facilities that handled them.

The developments unfolded as Attorney General John Ashcroft said investigators "are not able to rule out an association with the terrorist acts of September 11, but neither are we able to draw a conclusive link at this time."

Congress returned to work for the first time since an anthrax scare spread across Capitol Hill last week. House and Senate office buildings remained closed for additional environmental testing, and two sources, speaking on condition of anonymity, said authorities may decide to burn piles of mail for fear they could never check them adequately for anthrax.

As a precaution, the White House mail facility _ which is located outside the complex itself _ was being checked this week for evidence of anthax and new procedures were being put in place to ensure that the bacteria doesn't get carried into the West Wing via the mail, said a government official.

While several of those cases have connections to the news media, including ABC, CBS, NBC and the New York Post, the most recent developments depict a postal service work force at risk.

In Washington, one senior Postal Service official said roughly 3,400 employees across the nation's capital need to be evaluated and get at least 10 day's worth of antibiotics.

More than 2,000 workers at Brentwood, where anthrax has been found in 14 spots, will need a full 60-day course. Those at auxiliary offices were beginning preventive treatment while their work sites are tested.

In all, Walks said, the city knew of two patients hospitalized with inhalation anthrax, two postal workers confirmed dead of the disease and four people with symptoms that are suspicious. He said officials are watching another 12 cases but they are of "very low suspicion" for anthrax.

The disclosure came as New Jersey Health Commissioner George DiFerdinando said a mail handler in his state was believed to have contracted inhalational anthrax and was hospitalized in serious but stable condition. The woman works at a facility that processed at least three anthrax-tainted letters mailed to Washington and New York.

The FBI confirmed it is investigating whether other anthrax letters were processed through the Brentwood facility in Washington. The only known tainted letter was delivered to Daschle's office. Investigators have been unable to explain the presence of anthrax on a mail handling machine that serves the House.

The central facility handles mail not only for congressional offices, but for the entire District of Columbia and was declared a crime scene Tuesday.

"It's a crime scene because someone has been murdered," said Deborah Willhite, a top Postal Service executive.

Postal workers from as far away as Baltimore lined up outside a district hospital for testing and a supply of antibiotics. Many are angry about the delay in treatment.

"We have not been treated right," said Veola Jackson, a spokesman for the postal workers' union at the Brentwood facility. "I think this could have been avoided when they first saw that first piece of mail on the Hill."

Several days elapsed between the discovery on Monday of anthrax-tainted mail in Daschle's office and initial testing at the Brentwood facility. Officials explained their decision by saying that initial testing was negative at one of the postal facilities that the letter had passed through after leaving Brentwood.

Thompson told a congressional hearing that if other cases of anthrax emerge, officials would begin testing and treatment not only at the site where it was discovered but at every postal facility that the letter passed through.

Speaking at the White House, House Democratic Leader Dick Gephardt expressed frustration with a recent statement by Tom Ridge, director of Homeland Security, who said the anthrax had not been "weaponized."

"The words are not particularly helpful," said Gephardt, D-Mo. "Obviously this stuff gets in the air and stays in the air. ... You can call it anything you want to call it. This is not safe stuff."

Gephardt added, "This is weapons-grade material."

Officials identified the two men who died of inhalational anthrax as Joseph P. Curseen, 47, and Thomas L. Morris Jr., 55.