Authorities declared a state of emergency in northern California, ravaged by fires at a time when several other western US states are also fighting flames.

California Governor Jerry Brown said the affected counties were Plumas, Shasta and Tehama, in the north of the state, where dozens of fires are currently raging. His declaration freed up funds to help fight the fires.

The most threatening blaze, dubbed Ponderosa, has already destroyed some 50 buildings and threatens over 200 others. The flames have engulfed about 39 square miles (10,000 hectares) of vegetation, according to state authorities.

Over 2,100 firefighters and 11 helicopters have contained the fires by 50 percent of their original magnitude.

In Plumas, a fire nicknamed Chips has destroyed 97 square miles and is just 23 percent contained.

Fires at Trinity Ridge and Mustang Complex in Idaho engulfed more than 293 square miles of vegetation and were contained by five and nine percent respectively.

Washington State was not spared, with the Taylor Bridge fire destroying 51 houses and damaging six others east of Seattle.

The flames destroyed about 35 square miles and was about 90 percent contained.

This summer has been especially challenging for US firefighters facing unprecedented fires in Colorado in June that killed two people and destroyed 350 homes.

In total, some 10,800 square miles have gone up in smoke in the US so far this year. Nearly 1,815 square miles of fires have raged in Oregon, the most affected state, according to federal authorities.