Death toll in California wildfire rises to 21

Death toll in the wildfire that swept through northern California, has risen to 21 as hundreds of firefighters are still battling the flames in multiple areas of the region.

Wildfires raging across broad swaths of northern California have hospitalised hundreds, and charred about 170,000 acres of land, damaged or destroyed at least 3,500 structures and forced nearly 20,000 residents to evacuate, local media reports said.

According to the National Interagency Fire Center, more than 2,700 firefighters and support personnel are battling the fires.

United States President Donald Trump has said that the federal government will stand with the people of California after the devastating wildfires blazing through the region led to a massive destruction.

"I want to say a few words to the people of California. Great state. Especially with those in Napa. Napa has been hit so hard. And Sonoma. As they deal with the tragic loss of life and property to devastating wildfires," CNN quoted Trump as saying in his first public comments on the deadly California wildfires.

"I spoke with Governor Brown last night to let him know that the federal government will stand with the people of California and we will be there for you in this time of terrible tragedy and need. And I just want to pay my warmest respects. They are going through a lot," he added.

The wildfire, driven by powerful winds, tore through Northern California on Monday, forcing evacuations and destroying structures in their path.

Officials expect the death toll to rise and the high winds in the coming days could complicate efforts to contain fires.

The Trump administration has also approved a federal disaster declaration for California in response to wildfires.

Earlier, California Governor Jerry Brown had requested federal assistance to combat the deadly fires and had also declared an emergency in eight counties, including Napa and Sonoma.

The Department of Homeland Security has said that the Federal Emergency Management Agency immediately agreed to the state's request for federal funds to help fight many of the fires.