The Santa Clara Public Health Department confirmed Friday the nation's second coronavirus patient with no relevant travel history or clear link to another infected person or at-risk group, indicating that the virus may be spreading undetected in local communities.

"This new case indicates that there is evidence of community transmission but the extent is still not clear," Dr. Sara Cody, director of the County of Santa Clara Public Health Department, said in a statement Friday. "I understand this may be concerning to hear, but this is what we have been preparing for. Now we need to start taking additional actions to slow down the spread of the disease."

The new case brings the total number of coronavirus cases in California to 10 and the total number of cases in the U.S. to at least 63.

"We also don't have any evidence to suggest this case is linked to any other case in California," Cody told reporters at a press conference. There are two other cases in the county, the health department said. But this one is different because the patient, an elderly woman, doesn't have a travel history or any known contact with a traveler or infected person.