More than 800 structures are threatened by a massive wildfire in central California that left at least three people injured as it burned through Los Padres National Forest. 

The Gifford Fire scorched more than 113 square miles of coastal Santa Barbara and San Luis Obispo counties, with 3 percent containment, according to a U.S. Forest Service update Monday evening. 

More than 1,900 personnel are battling the blaze that grew out of at least four smaller fires that erupted Friday along State Route 166 between Santa Maria and Bakersfield. The causes of the fires are under investigation. 

The National Weather Service’s Los Angeles office has warned that the fire continued to generate considerable smoke that will affect parts of Southwest California, noting that wildfire smoke is a health risk. Smoke was expected to move toward the south and east. 

The blaze threatened about 872 structures and forced the closure of the highway in both directions east of Santa Maria, a city of about 110,000 people in Santa Barbara County.