SANTA MARIA, Calif. (AP) — 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 129 square miles (334 square kilometers) of coastal Santa Barbara and San Luis Obispo counties, with 7% containment, according to a U.S. Forest Service update on Tuesday morning.

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 blaze is burning through steep terrain and creating a huge smoke column, said Capt. Scott Safechuck, a spokesperson with the Santa Barbara County Fire Department.

"A lot of it's in really inaccessible areas where even bulldozers can't even get into," Safechuck said, adding that aircraft is being added to the firefight.

The smoke will affect parts of Southwest California, the National Weather Service's Los Angeles office said, 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. About 65 miles (105 kilometers) northwest of Santa Barbara and 150 miles (240 kilometers) northwest of Los Angeles, the hilly agricultural region is dotted by sprawling California live oaks and Sycamore trees and is known for its strawberry fields and wine industry.

Firefighters made great progress on the west, north and east flanks of the fire and significant efforts were made to ensure structure protection on the south end, officials said in an update Monday evening. Two new base camps were being established on the north and east sides of the fire, allowing more efficient access to the fire perimeter. Officials said they expected more helicopters to be able to deliver significant water drops Tuesday with a drone doing reconnaissance.

A warming and drying trend was expected to continue from Wednesday through the weekend, with temperatures up to 90 to 100 degrees Thursday and Friday, with increasing fire behavior, officials said.

A motorist was hospitalized with burn injuries after getting out of his vehicle and being overrun by flames, U.S. Forest Service spokesperson Flemming Bertelson said. Two contract employees assisting firefighters were also hurt when their all-terrain vehicle overturned.

Ranchers evacuated cattle Monday as aircraft made water drops on the encroaching flames.