Multiple wildfires have ignited in Southern California in recent days, as investigators examine unusual possible ignition sources.

There are currently seven wildfires burning around Southern California, some of which are threatening homes and prompting evacuations. The largest of the ongoing wildfires is the Santa Rosa Fire on Santa Rosa Island in Channel Islands National Park,

Firefighters are racing to keep flames away from the Santa Susana Field Laboratory, a former nuclear and rocket testing site.

Californians in multiple regions are being urged to stay alert as multiple, fast-moving wildfires force widespread evacuations, with thousands already displaced and more communities at risk. Shelters are under pressure,

More than 33,000 people remain under evacuation orders after a brush fire broke out in Simi Valley, Calif. By Soumya Karlamangla and Amy Graff A fast-moving brush fire in a suburban community north of Los Angeles destroyed one home on Monday and threatened thousands more,

Photos showed structures ablaze in Simi Valley, California.

Cal Fire is preparing for a potentially active wildfire season as California faces dry vegetation heading into the summer.

Several fires sparked in the past day in California as firefighters continue to battle the Sandy Fire in Simi Valley. CBS News' Matt Gutman reports.