More than 1 million people in the Bay Area were under the brief tornado warning, which was lifted by 6:15 a.m.

San Francisco experienced its first-ever tornado warning early Saturday, stunning residents as a powerful storm swept through the Bay Area, bringing heavy rain and winds. The warning prompted a flood of social media posts from residents startled awake by emergency alerts.

Residents in portions of San Francisco and San Mateo counties were awoken early Saturday to a tornado warning from the National Weather Service. "Take shelter now in a basement or an interior room on the lowest floor of a sturdy building,