SAN FRANCISCO—The National Weather Service has issued a rare tornado warning for Contra Costa County after a trained weather spotter reported seeing a funnel cloud.

The weather service says the cloud was seen about 9 miles south of Oakley and could touch down in a rural area of the east San Francisco Bay-area county.

It's the second time in a week that a rare tornado warning was issued, after a tornado warning was issued Wednesday for Santa Clara county.

The weather service urged people to go to a basement or interior hallway or room and lie down.