The nationwide anthrax scare continued unabated Sunday, as three people who were involved with investigating the infection of an NBC News employee in New York were themselves found to have been exposed to the dangerous bacterium. 

The policeman and two lab technicians who discovered the anthrax at NBC's offices overlooking Rockefeller Plaza were themselves found to be carrying anthrax spores, New York City officials said in a press conference Sunday. 

On Saturday five employees in Florida were being tested for infection for the noncontagious but potentially deadly disease, a second NBC News employee in New York showed symptoms of infection, eight people in California were being tested for the disease, and a letter sent to a Microsoft office in Nevada tested positive. 

Mayor Rudolph Giuliani said Sunday that the police officer and the lab workers were being treated with antibiotics and expected to be fine. He emphasized that exposure to the spores does not necessarily mean they have the anthrax infection. 

"When they were tested, minuscule spores were found," Giuliani said. 

The mayor said the police officer who retrieved the envelope was found to have anthrax in his nose, as did one lab technician investigating the case. Another lab technician was found to have a spore on her face, Giuliani said. 

The five employees of American Media, Inc., in Boca Raton, Fla., tested positive for exposure to the bacterium, but not necessarily for infection. 

"It means they had an exposure," said Gerald McKelvey, a spokesman for American Media. "It doesn't mean they have anthrax." 

CDC spokeswoman Lisa Swenarski in Atlanta couldn't confirm the five employees had been exposed because testing was not complete. She said it would be another week before final results were in. 

"The health department did advise individuals down there on preliminary results, which [doesn't] mean a whole lot," she said. 

None of the five were sick or in the hospital, said Michael Kahane, the company's general counsel. 

Robert Stevens, 63, a photo editor at the Sun, one of several supermarket tabloids housed in American Media's headquarters, died Oct. 5 of respiratory anthrax infection, which is 90 percent fatal. 

Stevens' case was thought to be isolated until a sweep of the American Media building revealed anthrax spores in his computer keyboard and in the noses of two other employees, neither of whom came down with the disease. 

Health officials had been waiting for results of more than 35 anthrax tests checking employees and visitors to the company's headquarters, which investigators in white moon suits continued to search Saturday. About 20 postal employees who handled the company's mail were also awaiting test results. 

On Friday, the FBI agent said test results of 965 people who were in the building recently found no new infections. 

In New York City, officials confirmed that a second NBC employee seemed to be infected with the bacterium, with a low-grade fever, swollen lymph nodes and a rash. She was taking antibiotics and did not appear to be in serious danger, health officials said. 

"She's fine," said Neal Shapiro, the network's news president. 

Panic spread through New York Friday as news broke that Erin O'Connor, 38, an assistant to NBC Nightly News anchorman Tom Brokaw, was diagnosed with subcutaneous anthrax, a much less dangerous form of infection than the respiratory variant that killed Stevens. 

O'Connor noticed a dark-colored lesion three days after the letter was received; on Oct. 1, she began taking the antibiotic Cipro. When the lesion started developing characteristics of anthrax, "a very alert and astute clinician" ordered skin tests, said David Fleming, deputy director for the Centers for Disease Control and Prevention. 

The letter that infected O'Connor had been mailed to Brokaw from Trenton, N.J., on Sept. 18, one week after hijacked airliners crashed into the World Trade Center and the Pentagon, killing an estimated 6,000 people. Officials have not found any link between the terror attacks and the anthrax cases, or indeed between the Florida and New York outbreaks. 

The FBI could not immediately pinpoint where the letter was dropped because Trenton is a regional processing center for southern and central New Jersey, said Special Agent Sandra Carroll, a spokeswoman for the FBI's Newark office. 

"There's over 100 different collection boxes or post offices it could have come from," Carroll said. FBI agents were interviewing mail carriers in Trenton on Saturday as part of a joint investigation with postal inspectors, she said. 

Still, spooked New Yorkers scurried to emergency rooms and pharmacies for anthrax tests and prescriptions for Cipro. Some drugstores ran out, or limited the amounts they would sell to customers. 

A letter containing powder also was sent to The New York Times, but the newspaper said Saturday that the white substance in the envelope received by reporter Judith Miller — who co-wrote a recent best seller on bioterrorism — tested negative for anthrax. 

Results from additional tests by the CDC were not expected until Tuesday, Times spokeswoman Catherine Mathis said. 

Miller and about 30 co-workers in the area when the envelope was opened are taking antibiotics, and results of their anthrax tests will be released Monday, the newspaper said. 

In Tulare, Calif., between Fresno and Bakersfield in the state's Central Valley, eight people were tested for anthrax exposure Saturday after a woman living in the town of Pixley, her son and her accountant found a white powder inside a tax-refund letter. 

Four Tulare County Sheriff's deputies were called in to investigate, with the result that all seven people plus one other person went to the hospital. None tested positive for anthrax exposure as of Sunday morning, but tests were still ongoing and all eight were being treated with Cipro. 

In Nevada, Gov. Kenny Guinn said a third anthrax test on a letter sent from Malaysia to a Microsoft office in Reno came back positive, but added that the risk to public health was "very, very low." 

Four of six Microsoft employees who may have touched the contaminated letter tested negative for anthrax Sunday, Nevada health officials said.

Final test results for two others exposed to the letter won't be known until Monday, said Washoe County health officer Barbara Hunt. Preliminary tests on their nasal swabs were also negative for the bacteria.

All six people — five Microsoft employees and a family member — had some form of contact to the letter sent to the Reno office. So far, no one has tested positive for the disease or become ill.

In Malaysia, federal police spokesman Benjamin Hasbie said authorities had begun investigating the matter, but they are waiting for U.S. intelligence through official channels. 

"We realize that this is a serious thing," Hasbie told The Associated Press. "We are looking into this. We can give our fullest cooperation, but we need solid evidence to step up our investigation." 

An envelope with a powdery substance on the outside was found in the mail at CBS News' Washington bureau Saturday. The envelope was turned over to the FBI, and tests were negative for anthrax, CBS News spokeswoman Sandy Genelius said. 

The Associated Press contributed to this report