Three new cases of the new coronavirus were confirmed in California on Sunday, bringing the U.S. total to 11. Health officials predict there will be more cases in the coming days but have warned Americans not to panic.

The new cases are linked to travel to Wuhan, China, the epicenter of the outbreak that has shaken the stock market, caused a run on face masks, and prompted restrictions on travel.

In San Francisco, a woman visiting family in the Bay Area since Jan. 23 fell ill and has been in isolated at home, along with her relatives, officials announced Sunday afternoon.

Hours later, authorities in San Benito County said that a couple, both ages 57, were sick with the virus. The husband had visited Wuhan, and infected his wife; neither of them have left their home sick since becoming ill, authorities said.

“While the virus is considered a serious public health threat, based on current information, the risk to the general public in California and locally in San Benito County continues to be low at this time,” said Dr. Marty Fentersheib, the county health officer.

U.S. officials have said infected people are only contagious once they start showing symptoms, though there have been reports by doctors overseas of pre-symptomatic transmission.

More than 350 people have died in China since the outbreak began. A Chinese man in the Philippines became the first person to die outside China last week.

More than 17,000 people have been infected globally, though the vast majority are in China, where some 50 million people have been locked down in a desperate effort to control the spread of the virus.