The Canyon Fire started on Thursday afternoon, quickly expanding through the dry and steep terrain in Ventura and Los Angeles counties, covering over 22 square kilometers.

It was 25 per cent contained as of Friday afternoon, according to the Ventura County Fire Department.

The Gifford Fire had spread to 402 square kilometers by Friday morning with 15 per cent containment.

This blaze resulted from at least four smaller fires that began on August 1 along State Route 166, leading to closures in both directions east of Santa Maria, a city with approximately 110,000 residents.

It has injured at least four people. The causes of the fires are under investigation.

Wildfire risk will be elevated through the weekend across much of inland California as a heat wave gripping the area intensifies.

August and September are typically the most dangerous months for wildfires in the state.