SAN FRANCISCO (KGTV) – The first case of coronavirus with unknown origin has been confirmed in Northern California.

The resident hasn’t traveled overseas since the outbreak began, the CDC said Wednesday. It’s unknown how the patient got the virus.

"At this time, the patient's exposure is unknown. It's possible this could be an instance of community spread of COVID-19, which would be the first time this has happened in the United States. Community spread means spread of an illness for which the source of infection is unknown," the agency said in a statement.

"It's also possible, however, that the patient may have been exposed to a returned traveler who was infected."

The CDC says it’s working with the state and preparing for “possible community transmission.”

The public health system in Northern California was able to catch the case.

Meanwhile, San Diego’s second coronavirus patient was released from the hospital Monday.

UC San Diego Health made said earlier in the week it was no longer caring for anyone with confirmed or possible cases of the virus.