Health officials in San Jose said the patient was an older adult woman with chronic health conditions who does not have a travel history or any known contact with a traveler or infected person. It comes a day after state officials said a woman hospitalized at UC Davis Medical Center in Sacramento had contracted the illness after no known contact.

"This new case indicates that there is evidence of community transmission, but the extent is still not clear," said Dr. Sara Cody, health officer for Santa Clara County and director of the County of Santa Clara Public Health Department.

Officials were able to get quick confirmation because the test was done by the Santa Clara County Public Health Laboratory with test kits received from the federal Centers for Disease Control and Prevention. Officials submitted the woman's specimens for testing Thursday and received the results Thursday night.

The California Department of Public Health said Friday that the state will receive enough kits from the CDC to test up to 1,200 people, a day after Gov. Gavin Newsom complained to federal health officials that the state had already exhausted its initial 200 test kits.

State official also said the federal government decided it will not need to use the Fairview Developmental Center in Orange County to isolate passengers from the Diamond Princess cruise ship. That's because of the imminent end of the isolation period for those passengers and the relatively small number of persons who ended up testing positive, officials said.

The CDC had originally estimated that as many as half the passengers would test positive. But the state said the actual number has been "substantially lower." A federal judge had granted officials in Costa Mesa a temporary restraining order blocking the transfers during the time when state officials said the facility had been "critically needed."

Cody said the newly confirmed case in Santa Clara County is not linked to two previous cases in that county, nor to others in the state.

The Santa Clara County resident was treated at a local hospital and is not known to have traveled to Solano County, where public health officials have identified dozens of people — but less than 100 — who had close contact with the case announced Thursday. They are quarantined in their homes. and a few who have shown symptoms are in isolation, officials said.

At UC Davis Medical Center, at least 124 registered nurses and other health care workers were sent home for "self-quarantine" after the woman with the virus was admitted, National Nurses United, a nationwide union representing RNs, said Friday.

"Despite University of California medical facilities being generally better prepared and equipped to treat challenging medical cases, the ... case highlights the vulnerability of the nation's hospitals to this virus," the union said.

The case of the infected women marks an escalation of the worldwide outbreak in the U.S. because it means the virus could spread beyond the reach of preventative measures like quarantines, though state health officials said that was inevitable and that the risk of widespread transmission remains low.

California public health officials on Friday said more than 9,380 people are self-monitoring after arriving on commercial flights from China through Los Angeles and San Francisco. That's up from the 8,400 that Newsom cited on Thursday, though officials said the number increases daily as more flights arrive.

Officials are not too worried, for now, about casual contact, because federal officials think the coronavirus is spread only through "close contact, being within six feet of somebody for what they're calling a prolonged period of time," said Dr. James Watt, interim state epidemiologist at the California Department of Public Health.

The virus can cause fever, coughing, wheezing and pneumonia. Health officials think it spreads mainly from droplets when an infected person coughs or sneezes, similar to how the flu spreads.

As infectious disease experts fanned out in the Solano County city of Vacaville, some residents in the city between San Francisco and Sacramento stocked up on supplies amid fears things could get worse despite official reassurances, while others took the news in stride.

The woman in the community who has coronavirus first sought treatment at NorthBay VacaValley Hospital in Vacaville, before her condition worsened and she was transferred to the medical center in Sacramento.

Sacramento County's top health official told The Sacramento Bee on Friday that he expects several medical workers to test positive themselves in the next few days. Numerous workers at both hospitals have been tested, but the tests were sent to labs approved by the CDC and generally take three to four days to complete.

Peter Beilenson, Sacramento County's health services director, said he expects even those who test positive to become only mildly ill.

Confusion over how quickly the woman was tested for coronavirus concerned McKinsey Paz, who works at a private security firm in Vacaville. The company has already stockpiled 450 face masks and is scrambling for more "since they're hard to come by." The company's owner bought enough cleaning and disinfectant supplies to both scrub down the office and send home with employees.

But they appeared to be at the extreme for preparations.

Eugenia Kendall was wearing a face mask, but in fear of anything including the common cold. Her immune system is impaired because she is undergoing chemotherapy, and she has long been taking such precautions.

"We're not paranoid. We're just trying to be practical," said her husband of 31 years, Ivan Kendall. "We wipe the shopping carts if they have them, and when I get back in the car I wipe my hands — and just hope for the best."

Experts in both communities are interviewing immediate family members and expanding their net to include more distant family members who may have been in contact, social gatherings like church that the patient may have attended and any possible time spent at work or events like a concert.

Besides the woman, all the other cases in the U.S. have been for people who traveled abroad or had close contact with others who traveled.

Earlier U.S. cases included 14 in people who returned from outbreak areas in China, or their spouses; three people who were evacuated from the central China city of Wuhan; and 42 American passengers on the Diamond Princess cruise ship.

The number of people sickened by the virus hovered Friday around 83,000, and there were more than 2,800 deaths, most of them in China.