Massive wildfire has forced hundreds of people to evacuate their homes in Los Angeles as California governor declared a state of emergency.

Water is dropped above homes in Sun Valley during the La Tuna Canyon fire over Burbank, California, US, September 2, 2017.
Water is dropped above homes in Sun Valley during the La Tuna Canyon fire over Burbank, California, US, September 2, 2017. (Reuters)

A huge fire described as the biggest in the history of Los Angeles was raging on Saturday, forcing hundreds of people to evacuate their homes.

Mayor Eric Garcetti told reporters the blaze, which broke out Friday and lit up the hills surrounding the northern suburb of Burbank overnight, had already burnt 2,000 hectares.

"In terms of hectares involved this is probably the largest fire in L.A. city history." he added.

The Los Angeles fire was one of several major fires in the western United States.

The federal government declared state of emergencies in Montana and Washington state, where thousands of people have been evacuated.

Such emergencies are declared to release and mobilise federal resources to help fight the fires.

In Los Angeles, Garcetti has declared local state of emergency and he appealed to California Governor Jerry Brown to do the same at the state level.

The Los Angeles blaze has so far destroyed three structures, including two houses, and forced the evacuation of nearly 700 homes in various parts of the city and neighbouring Glendale, firefighters said.

Evacuation orders

Flames were visible in the hills in several neighbourhoods including Burbank, where the Disney and Warner Bros. studios are located.

More than 500 firefighters were mobilised, while 100 others who had been deployed in Houston, Texas to help rescue operations after Hurricane Harvey were asked to return.

The fire, which is only ten percent controlled, broke out on the US Labor Day holiday long weekend and as the western part of the country was facing a summer heatwave.

Some access roads to the famed Yosemite National Park have been closed due to fire, as have hiking trails.

"Expect poor air quality and limited visibility due to fires in Yosemite," the park said on its website.

Authorities said wind was their main concern because it could whip up the flames and allow it to spread quickly in unpredictable directions.

Further north in Washington state, more than 4,000 homes have been evacuated because of the dangers posed by a number of fires covering 6,000 hectares.

High temperatures are forecast for the state over the next week, which could complicate firefighting efforts.

Massive forest fires also prompted evacuations in neighbouring Oregon.

In Montana, more than 20 fires were burning as near record high temperatures, wind and below normal rainfall have created a tinder box.

Wildfires in the US West have burned more than 2.9 million hectares since the beginning of the year, about 50 percent more than during the same time period in 2016, according to the National Interagency Fire Center.

Source: TRTWorld and agencies