Cal Fire crews are responding to the scene of a brush fire in Ramona that broke out early Tuesday morning, threatening at least one structure.

"If fire ignition occurs, conditions are favorable for very rapid fire spread and extreme fire behavior," the NWS warns.

Red-flag fire warnings are in place for 2 million people in Southern California, with extreme fire conditions expected through at least Wednesday. Tropical-storm-strength winds could fan the flames around the Los Angeles area and send ash and embers through the air.