A fast-moving wildfire has burned through nearly 90 square kilometres of land, prompting hundreds of people to flee from their homes in the drought-parched foothills northwest of Los Angeles.

The so-called Sand Fire broke out shortly after 2 p.m. on Friday in the Sand Canyon area of suburban Santa Clarita, triggering mandatory evacuation orders. 

The wildfire threatened at least 1,500 homes, an animal sanctuary, and around 100 commercial structures.

Winds pushed the blaze into the adjacent Angeles National Forest, and it rapidly gained ground within hours in the hot weather and drought conditions.

"Because this is the fifth year of an ongoing drought, we have a lot [of] dry vegetation," Los Angeles County Fire Chief Daryl Osby said at a news conference on Saturday, adding that some of these fuels "haven't burned in decades".

The wildfire had burned through 45 square kilometres of land by Saturday afternoon, expanding to 90 square kilometres by Saturday evening.

Los Angeles County Sheriff's homicide detectives were investigating circumstances surrounding a man found dead in an evacuation area.

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Around 900 firefighters were battling the blaze in temperatures exceeding 41 degrees Celsius, aided by 28 water-dropping helicopters and eight fixed-winged aircraft. 

By late Saturday night, the Southern California blaze was about 20 percent contained.

Due to the thick smoke blanketing much of Los Angeles, South Coast Air Quality Management District issued a smoke advisory, warning of unhealthy air conditions in the region.

Evacuation shelters have been set up for residents in the area, and about 10 roads have been closed. 

This blaze is the most recent in a series of fires that have hit the drought-stricken state, spurred on by high heat and very low humidity. 

In September 2015, a state of emergency had been declared in the northern areas of California due to a wildfire that forced thousands of people to evacuate small towns. 

Deadly California wildfire ravages homes

Source: Agencies