Powerful storms swept through parts of Northern California on Saturday, knocking down trees, causing widespread power outages and prompting weather officials to issue what they said was the first-ever tornado warning for San Francisco.

San Francisco residents were woken up by a tornado warning early Saturday morning during a powerful storm system that battered the region with heavy rain and wind.

A tornado warning was issued by the NWS San Francisco CA on Saturday at 5:51 a.m. "At 5:51 a.m., a severe thunderstorm capable of producing a tornado was located near Daly City, moving northeast at 45 mph,