A New York Post employee and a second Trenton, N.J., postal worker have been infected with skin anthrax, becoming the seventh and eighth anthrax cases nationwide in recent weeks. The New York victim also became the fourth in New York City — all involving media companies.

The Post said in a statement Friday that the victim, a 30-year-old woman, was on the support staff for the editorial page editor. She has returned to work and is expected to recover.

The postal worker, a 35-year-old man from Levittown, Pa., loads mail at a regional mail center in Hamilton, N.J. A female mail sorter at the same facility was diagnosed with cutaneous anthrax on Thursday. 

In Washington, Homeland Security Director Tom Ridge said anthrax strains discovered in Florida, New York and Washington are indistinguishable from one another, and have not been "weaponized."

"It does appear that it may have come from the same batch," Ridge said at a White House news conference. He added, "It may have been distributed to different individuals to infect and descend into different communities."

He also said the FBI had been able to identify the site where anthrax-tainted letters had been mailed to Senate Majority Leader Tom Daschle and NBC anchorman Tom Brokaw. "It was a mailbox," Ridge said of the letter postmarked from the Trenton, N.J., area.

He said that so far there are no test results to suggest the anthrax had been weaponized, meaning altered to make it spread more easily in the air.

Ridge also said the administration was preparing for the threat of additional anthrax attacks.

"I wish I could tell you that we have seen the end of it, but obviously we are preparing for more. That's why we have increased the supply of antibiotics," he said.

The Post said the source of its employee's anthrax was not known and additional tests were being done at its offices in midtown Manhattan. 

Post Co-Chairman Lachlan Murdoch said the woman's work included opening letters to the editor, but "she doesn't recall opening any suspicious letters or packages."

The woman noticed a blister on one of her fingers on Sept. 22. The blister became infected, and she was treated with antibiotics. After the discovery of anthrax at NBC last week, she was tested for anthrax, the newspaper said in a statement.

Early tests were negative, but a positive test came back Thursday night. As a precaution, three other members of the Post staff who displayed flu-like symptoms were tested for anthrax in the past week. Those tests all were negative.

"We are taking every precaution and working closely with authorities to identify the source of the infection and prevent any further risk," Post Publisher Ken Chandler said. "The authorities have assured us there is no danger to our employees."

Murdoch said the FBI and Centers for Disease Control and Prevention were conducting a criminal investigation at the Post. "This is not a health investigation," he said outside the building.

Mayor Rudolph Giuliani continued to emphasize that all the city's anthrax cases were isolated and cured.

"At this point, there's no reason for anyone to be overly alarmed," the mayor said. "We have four people who have contracted anthrax; four people are cured."

The New York Post is located at the News Corp. building on New York's Avenue of the Americas. No other cases have been found at the building, which is also the headquarters for Fox News.

Fox News and the New York Post are both owned by News Corp., a worldwide media organization headed by Rupert Murdoch.

The building was one of several media headquarters in Manhattan checked by police and the Health Department for the presence of anthrax over the past week.

The Trenton, N.J., mail sorter was in stable condition at a hospital, is taking antibiotics and is expected to recover, Pennsylvania Department of Health spokesman Richard McGarvey said.

"It isn't life threatening in any way," McGarvey said.

Officials said they believed a third postal worker at the New Jersey facility, a maintenance worker who serviced mail-sorting machines,  was "almost certain" to have anthrax. Test results are still pending in that case.

The latest confirmed infections came as federal investigators tried to find those responsible for spreading the potentially deadly bacteria.

As officials sought to allay public concern, police declared two Senate office buildings off-limits to check the spread of spores on Capitol Hill. "No member, staff member or congressional employee will be permitted to enter" the Dirksen or Hart Senate office buildings without personal protection gear," said a memo issued by officials.

One man has died and a second man remains ill in Florida after inhaling anthrax spores. Other cases of a less dangerous form of the disease have been traced to a letter mailed to NBC anchorman Tom Brokaw in New York.

Another 31 people initially tested positive for exposure in Washington after the delivery of an anthrax-tainted letter to the office of Senate Majority Leader Tom Daschle. Officials, speaking on condition of anonymity, said that after additional tests, three of the 31 have been determined not to have been exposed.

The developments came as federal investigators struggled to trace the origin of a spate of anthrax-bearing letters, and administration officials said they still had no evidence of a connection between the bioterrorism and the Sept. 11 suicide hijackings that killed more than 5,000 people.

"I do not have knowledge of a direct link of the anthrax incidents to the enemy, but I wouldn't put it past them," President Bush said at a news conference in China.

Six people had previously been diagnosed with anthrax in the past two weeks, including one Thursday at a New Jersey postal facility where tainted letters to Daschle and Brokaw were processed. Officials theorize the infected letter carrier and the mail sorter diagnosed today may may have handled the envelopes at the Trenton post office facility.

Officials also disclosed Thursday that the woman who opens CBS anchorman Dan Rather's mail had been infected with the treatable skin form of the disease.

Anthrax has been discovered in two Senate office buildings: in a mail facility in the Dirksen building and in Daschle's office in the Hart building. The Senate memo declared the buildings to be a "warm zone," but police spokesman Dan Nichols said that was a routine designation in situations in which testing for hazardous materials was undertaken.

One congressional source, speaking on condition of anonymity, said another 1,300 people at the Capitol showed no sign of exposure in tests completed overnight. Hundreds more awaited their results.

Thirty-one people tested positive for exposure to anthrax earlier this week after powdery substance fell from mail opened in Daschle's office. They included 23 aides to the majority leader, five police officers and three people on the staff of Sen. Russ Feingold, D-Wis., who occupies the office next to Daschle's.

Customers who visited the West Trenton post office in the past three weeks were urged to see a doctor if they had any symptoms of illness or a rash.

One scenario being explored is whether someone living in the United States might have worked with a foreign country or an overseas domestic terrorist group with enhanced biochemical capabilities, officials said.

"We think it may be ill-advised to think about the situation in terms of an either-or matrix," Attorney General John Ashcroft said. He also raised the possibility that the anthrax attacks could be the work of more than one homegrown terrorist.

"It might well be that we have opportunists in the United States or terrorists in the United States who are acting in ways that are unrelated," the attorney general added.

Ashcroft said that he could not rule out a connection between the anthrax attacks and the events of Sept. 11.

The Associated Press contributed to this report.